【单选题】【消耗次数：1】
3. He ______ hard until I told him to sit down and have a break.
①
was working
②
had been working
③
worked
④
has worked
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相关题目
【单选题】
Had he worked hard, he _____ the exams.
①
must have got through
②
would have got through
③
would get through
④
could get through
【单选题】
If he had worked harder, he ___.
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would succeed
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had succeeded
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should succeed
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would have succeeded
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make out for
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keep up with
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catch up with
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make up for
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The boy worked hard ______ he could get the prize.
①
so that
②
so as to
③
so as
④
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【单选题】
He____________ working as if nothing had happened.
①
continue
②
continues
③
continuing
④
continued
【判断题】
Before he began to study in the university, he had worked in a company for three years.
①
正确
②
错误
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Tom is hard-working, so its _____________ that he won the match.
①
no wonder
②
a pity
③
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④
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【单选题】
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①
opportunity
②
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③
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随机题目
【单选题】
<img class="kfformula" src="20200629/1593404929347068.png" data-latex="{^{35}_{17}C1}与{^{37}_{17}C1}互为（\, \, \, ）。" width="206" height="30"/>
①
同系物
②
同种物质
③
同位素
④
同素异形体
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关于元素周期律和元素周期表的下列说法，正确的是( )。
①
俄国化学家道尔顿为元素周期表的建立做出了巨大的贡献
②
同一主族的元素从上到下，金属性呈周期性变化
③
目前发现的所有元素占据了周期表里全部位置，不可能再有新的元素被发现
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元素的性质随着原子序数的增加而呈周期性变化
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下列对沉淀溶解平衡的描述正确的是( )。
①
反应开始时，溶液中各离子浓度相等
②
沉淀溶解达到平衡时，如果再加入难溶性的该沉淀物，将促进溶解
③
沉淀溶解达到平衡时，溶液中溶质的离子浓度相等，且保持不变
④
沉淀溶解达到平衡时，沉淀的速率和溶解的速率相等
【单选题】
钢铁在锈蚀过程中，下列5种变化可能发生的是（ ）。①Fe由+2价转化为+3价 ②<img class="kfformula" src="20200629/1593421096381805.png" data-latex="{O}_{2}" width="35" height="32"/>被还原 ③产生<img class="kfformula" src="20200629/1593421096272347.png" data-latex="{H}_{2}" width="41" height="27"/> ④<img class="kfformula" src="20200629/1593421096882976.png" data-latex="{Fe(OH)}_{3}" width="97" height="32"/>失水形成<img class="kfformula" src="20200629/1593421096337573.png" data-latex="{Fe}_{2}{O}_{3}\cdot {H}_{2}" width="90" height="35"/>⑤杂质碳被氧化除去
①
③④
②
①②③④
③
①②
④
①②③④⑤
【单选题】
下列物质存放方法正确的是（）。
①
少量的钠保存在无水乙醇中
②
药品柜的同一层不可存放浓硝酸和浓氨水
③
硅酸钠溶液保存在玻璃塞的试剂瓶中
④
少量白磷保存在二硫化碳中
【单选题】
下面的说法正确的是（）。
①
硫酸钡不溶于水，所以硫酸钡是非电解质
②
固态磷酸是电解质，所以磷酸在熔化时或溶于水时都能导电
③
二氧化碳溶于水可以导电，所以，二氧化碳是电解质
④
液态氯化氢不能导电，但氯化氢是电解质