【判断题】【消耗次数:1】
两刚片或三刚片组成几何不变体系的规则中,不仅指明了必需的约束数目,而且指明了这些约束必须满足的条件。
正确
错误
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相关题目
【单选题】 三刚片组成几何不变体系的规则是( )
①  三链杆相联,不平行也不相交于一点
②  三铰两两相联,三铰不在一直线上
③  三铰三链杆相联,杆不通过铰
④  一铰一链杆相联,杆不过铰
【判断题】 几何不变体系的组成规则有三刚片规则、两刚片规则、二元体规则三个。
①  正确
②  错误
【判断题】 两个刚片用三根交于同一点的链杆相联,组成几何不变体系。()
①  正确
②  错误
【单选题】 将三钢片组成无多余约束的几何不变体系,必要的约束数目是( )个。
①  4
②  3
③  6
④  2
【单选题】 一个点和一个刚片用( )的链杆相连,组成几何不变体系。
①  两根共线的链杆
②  两根不共线的链杆
③  三根不共线的链杆
④  三根共线的链杆
【单选题】 下列不能组成无多余约束的几何不变体系是()。
①  三刚片以3个铰两两相联,3个铰不在一条直线上
②  二刚片以3个链杆相联,3个链杆不平行也不汇交
③  二刚片以1个铰和1个链杆相联
④  在一个刚片上加二元体
【单选题】 下列哪种情况不能组成无多余约束的几何不变体系( )。
①  三刚片以3个铰两两相联,3个铰不在一条直线上
②  二刚片以3个链杆相联,3个链杆不平行也不汇交
③  刚片上加二元体
④  二刚片以1个铰和1个链杆相联
【判断题】 两个刚片用三根不全平行也不交于同一点的链杆相联,组成几何不变体系,且没有多余联系。()
①  正确
②  错误
【判断题】 两个刚片用三根平行但不等长的链杆相联,组成几何瞬变体系。()
①  正确
②  错误
【判断题】 三刚片由三个单铰或任意六根链杆两两相联,体系必为几何不变。
①  正确
②  错误
随机题目
【单选题】 Trees mainly serve man in three important ways: They provide him with wood and other products; they provide him shade; and they help to prevent droughts and floods.Unfortunately, in many parts of the world, man has not realized that the third of these services is the most important.In his eagerness to make money from trees, he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And besides, he is usually too careless to plant and look after new trees. So the forests slowly disappear.This does not only mean that man will have fewer trees. The results are even more serious: for where there are trees, their roots break up soil allowing the rain to sink in and also bind(固定) the soil, thus preventing it from being washed away easily;but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When the top-soil is gone, nothing remains but worthless desert.Two thousand years ago,a rich and powerful country cut down its trees to build warships, with which to gain itself an empire.It set up the empire, but, without its trees, its soil became poor and grew weak. When the empire fell to pieces, the home country found itself faced by floods and starvation(饥荒).According to the passage, which is the most important service of trees to man?
①  They help him make money.
②  They give him cool.
③  They give him wood and other things.
④  They help him to stop droughts and floods.
【单选题】 Trees mainly serve man in three important ways: They provide him with wood and other products; they provide him shade; and they help to prevent droughts and floods.Unfortunately, in many parts of the world, man has not realized that the third of these services is the most important.In his eagerness to make money from trees, he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And besides, he is usually too careless to plant and look after new trees. So the forests slowly disappear.This does not only mean that man will have fewer trees. The results are even more serious: for where there are trees, their roots break up soil allowing the rain to sink in and also bind(固定) the soil, thus preventing it from being washed away easily;but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When the top-soil is gone, nothing remains but worthless desert.Two thousand years ago,a rich and powerful country cut down its trees to build warships, with which to gain itself an empire.It set up the empire, but, without its trees, its soil became poor and grew weak. When the empire fell to pieces, the home country found itself faced by floods and starvation(饥荒).Which title best fits the passage?
①  Trees and Man
②  The Function of Tree Wood
③  How do People do with Trees?
④  The Usage of Tree Roots
【单选题】 Trees mainly serve man in three important ways: They provide him with wood and other products; they provide him shade; and they help to prevent droughts and floods.Unfortunately, in many parts of the world, man has not realized that the third of these services is the most important.In his eagerness to make money from trees, he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And besides, he is usually too careless to plant and look after new trees. So the forests slowly disappear.This does not only mean that man will have fewer trees. The results are even more serious: for where there are trees, their roots break up soil allowing the rain to sink in and also bind(固定) the soil, thus preventing it from being washed away easily;but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When the top-soil is gone, nothing remains but worthless desert.Two thousand years ago,a rich and powerful country cut down its trees to build warships, with which to gain itself an empire.It set up the empire, but, without its trees, its soil became poor and grew weak. When the empire fell to pieces, the home country found itself faced by floods and starvation(饥荒).Why did the country mentioned in the passage suffer from floods and starvations?
①  Because it set up an empire.
②  Because it fell to pieces.
③  Because it turned its trees into warships.
④  Because it spent too much money on wars.
【单选题】 Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight(困境)while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump(垃圾场)was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump. The city government faces a serious problem because __________.
①  fires destroyed thirty homes in a neighborhood four years ago
②  the speed of rebuilding the houses is really too slow
③  the overgrowing plants in this area have made the city look terrible
④  the overgrowing plants in this area have become a big danger of fire
【单选题】 Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight(困境)while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump(垃圾场)was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump. Why was the goat-keeper chosen to remove the bushes?
①  Because he offered to do it for the lower price.
②  Because it was easier to transport his goats.
③  Because his goats can do the job better.
④  Because the city wanted to raise more goats.
【单选题】 Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight(困境)while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump(垃圾场)was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump. What are the “two birds” that the city government kills with only one stone?
①  Both the sheepherder and goat-keeper will work for the city for $25,000.
②  The danger of fire and providing breakfast and lunch for the work crews.
③  The danger of fire and the overflowing dump.
④  The city government can save some money and the goat-keeper has a new job.
【单选题】 Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight(困境)while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump(垃圾场)was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump. According to the passage, __________.
①  the sheepherder offered to do the job for $50,000
②  the lowest bid to remove the bushes was $50,000
③  the sheepherder and the goat-keeper were both addicted to surfing the Internet
④  hiring goats to do the job saved the city government lots of money
【单选题】 Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight(困境)while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump(垃圾场)was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump. What can be inferred from the passage?
①  The city will remove the bushes in this area regularly.
②  The goat-keeper asked for $50,000 to kill the birds with stones.
③  The goat-keeper was invited to San Diego to do some sightseeing.
④  The city government was not kind to the people who worked for it.
【单选题】 Susan: How do you do, Mrs. White.Mrs. White: How do you do, Susan. I’m glad you can join us. __________
①  Don’t be shy.
②  Please feel natural.
③  Make yourself at home.
④  Feel all right here.
【单选题】 Tommy: Mommy, when will we have dinner? I’m starving.Mother: __________ We have to wait for Daddy.
①  OK, honey.
②  Quickly, honey.
③  Soon, honey.
④  All right, honey.