【单选题】【消耗次数：1】
Someone called me up in the middle of the night, but they hung up _____ I could answer the phone.
①
as
②
since
③
until
④
before
参考答案：
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相关题目
【单选题】
A: Could you help me put up the posters on the wall? B: [填空].
①
I will
②
No problem
③
I would like
④
Thats a good idea
【单选题】
I was caught up ___________ conversation with a friend when someone knocked at the door.
①
in
②
at
③
over
④
off
【单选题】
A: Do you know Marks phone number? B: [填空] . A: OK. I might as well look it up in the phone book.
①
Just a second
②
Not that I know of
③
I cant think of it now
④
Why ask?
【单选题】
I ____ up early this morning, so I stayed in bed until 8 o’clock a.m. .
①
needn’t have got
②
didn’t need to get
③
shouldn’t have got
④
can’t have got
【单选题】
did you sleep last night? I stayed up too late to go to sleep.
①
?How
②
When
③
Why
④
?Where
【单选题】
18.- ______ did you sleep last night? - I stay up too late to go to sleep.
①
How
②
When
③
Why
④
Where
【单选题】
You must have stayed up late last night, _____?
①
mustn’ t you
②
don’ t you
③
didn’ t you
④
needn’ t you
【单选题】
2. Whenever I called in on Paul, he _______ on the phone.
①
talked
②
is talking
③
was talking
④
will talk
【单选题】
Thats pretty good that you get up and go running, but I ______ like running early in the morning since I’ve got to prepare breakfast for my family.
①
have a good time
②
have a hard time
③
have time
④
have much time
随机题目
【多选题】
下列矩阵中秩为3的是
①
<img src=https://huaweicloudobs.ahjxjy.cn/3C85D528093498275A366020E887D5E2.png title=1.png alt=1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/C9967D5A3C80E341D4875E2F457DF20D.png title=2.png alt=2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/ECA4AD96D4BC730D1D6A66FE13B6F845.png title=3.png alt=3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/EDEE3F5BC73816589275FDB73F95AB3F.png title=4.png alt=4.png/>
【判断题】
如果矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=vertical-align: middle;/>可逆，则它的逆矩阵不是唯一的。
①
正确
②
错误
【多选题】
下列说法不正确的是
①
矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=vertical-align: middle;/>的秩<img class=jc-formula data-tex=r src=https://huaweicloudobs.ahjxjy.cn/E9923AD0A374BFA71C0398F679429095.png style=vertical-align: middle;/>就是矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>中不为零的子式的最高阶数。
②
如果矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>的秩<img class=jc-formula data-tex=r(A)=r src=https://huaweicloudobs.ahjxjy.cn/E373C4598E30C10358A79462A2E95326.png style=vertical-align: middle;/>，则矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>中可能存在<img class=jc-formula data-tex=r+1 src=https://huaweicloudobs.ahjxjy.cn/BB0E3B92B0A6885A756EDDFBF33A6887.png style=vertical-align: middle;/>阶非零子式。
③
如果矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>的秩<img class=jc-formula data-tex=r(A)=r src=https://huaweicloudobs.ahjxjy.cn/E373C4598E30C10358A79462A2E95326.png style=white-space: normal; vertical-align: middle;/>，则矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>中不可能存在<img class=jc-formula data-tex=r+1 src=https://huaweicloudobs.ahjxjy.cn/BB0E3B92B0A6885A756EDDFBF33A6887.png style=white-space: normal; vertical-align: middle;/>阶非零子式。
④
初等变换法会改变矩阵的秩。
【多选题】
矩阵<img class=jc-formula data-tex={ A }_{ n\times n } src=https://huaweicloudobs.ahjxjy.cn/772C42B20C708CB748428EB11DB31937.png style=vertical-align: middle;/>可逆的充要条件是
①
矩阵<img class=jc-formula data-tex={ A }_{ n\times n } src=https://huaweicloudobs.ahjxjy.cn/772C42B20C708CB748428EB11DB31937.png style=white-space: normal; vertical-align: middle;/>非奇异
②
矩阵<img class=jc-formula data-tex={ A }_{ n\times n } src=https://huaweicloudobs.ahjxjy.cn/772C42B20C708CB748428EB11DB31937.png style=white-space: normal; vertical-align: middle;/>可以表示为一些初等矩阵的乘积
③
矩阵<img class=jc-formula data-tex={ A }_{ n\times n } src=https://huaweicloudobs.ahjxjy.cn/772C42B20C708CB748428EB11DB31937.png style=white-space: normal; vertical-align: middle;/>的等价标准形为同阶单位矩阵。
④
矩阵<img class=jc-formula data-tex={ A }_{ n\times n } src=https://huaweicloudobs.ahjxjy.cn/772C42B20C708CB748428EB11DB31937.png style=white-space: normal; vertical-align: middle;/>非满秩。
【多选题】
<img src=https://huaweicloudobs.ahjxjy.cn/BAC58463BEBC00197646A358AFAE271D.png title=7.png alt=7.png/>则下面计算结果正确的是
①
<img class=jc-formula data-tex=x=-6 src=https://huaweicloudobs.ahjxjy.cn/AE5BA349FC9693508A243E2AE08D13A1.png style=vertical-align: middle;/>
②
<img class=jc-formula data-tex=y=-5 src=https://huaweicloudobs.ahjxjy.cn/B5D1A61B2C37E6F20493277846F1D480.png style=vertical-align: middle;/>
③
<img class=jc-formula data-tex=u=4 src=https://huaweicloudobs.ahjxjy.cn/A5CEAEB0A049DBC6AC8C0216CF47973D.png style=vertical-align: middle;/>
④
<img class=jc-formula data-tex=v=-2 src=https://huaweicloudobs.ahjxjy.cn/C246D1F1AC652DDD54D6464CD042C2A7.png style=vertical-align: middle;/>
【判断题】
数<img class=jc-formula data-tex=k src=https://huaweicloudobs.ahjxjy.cn/489644C6054AE2D1C361472A2F0472E9.png style=vertical-align: middle;/>乘以矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=vertical-align: middle;/>就是用数<img class=jc-formula data-tex=k src=https://huaweicloudobs.ahjxjy.cn/489644C6054AE2D1C361472A2F0472E9.png style=white-space: normal; vertical-align: middle;/>乘以矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>的某一行（列）元素。
①
正确
②
错误
【多选题】
下列说法正确的是
①
如果<img class=jc-formula data-tex=n src=https://huaweicloudobs.ahjxjy.cn/11056C1B8875D4D8E374CB0C6A7248B5.png style=white-space: normal; vertical-align: middle;/>阶矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>中满足<img class=jc-formula data-tex={ a }_{ ii }=0 src=https://huaweicloudobs.ahjxjy.cn/5BF08368B73074086596DB646C2CBDE5.png style=white-space: normal; vertical-align: middle;/>，则称<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>为对称矩阵。
②
如果<img class=jc-formula data-tex=n src=https://huaweicloudobs.ahjxjy.cn/11056C1B8875D4D8E374CB0C6A7248B5.png style=white-space: normal; vertical-align: middle;/>阶矩阵<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>中满足<img class=jc-formula data-tex={ a }_{ ij }={ a }_{ ji },(i,j=1,2,\cdots ,n) src=https://huaweicloudobs.ahjxjy.cn/EE6F4A09E65EB096D9D071E561C1FF42.png style=vertical-align: middle;/>，则称<img class=jc-formula data-tex=A src=https://huaweicloudobs.ahjxjy.cn/60BDCDAB2585C1363A4374A112B62C6E.png style=white-space: normal; vertical-align: middle;/>为对称矩阵。
③
数乘对称矩阵仍为对称矩阵。
④
对称矩阵乘积仍然对称。
【多选题】
<img src=https://huaweicloudobs.ahjxjy.cn/631A67ABC7C0AA0DB0C7B9BEE9A1849E.png title=5.png alt=5.png/><img src=https://huaweicloudobs.ahjxjy.cn/EC8583C8AA766F69070257512104A8D4.png title=6.png alt=6.png/>则下面计算结果正确的是
①
<img class=jc-formula data-tex=a=\frac { 1 }{ 3 } src=https://huaweicloudobs.ahjxjy.cn/A4FC0D089B3E34A4C9C765EFDCB415BC.png style=vertical-align: middle;/>
②
<img class=jc-formula data-tex=a=-\frac { 2 }{ 3 } src=https://huaweicloudobs.ahjxjy.cn/4B2120C41DECCC8AFE70663918986066.png style=vertical-align: middle;/>
③
<img class=jc-formula data-tex=b=0 src=https://huaweicloudobs.ahjxjy.cn/9A81261EDFE166EEDF6D639A4EE5E39C.png style=vertical-align: middle;/>
④
<img class=jc-formula data-tex=c=-\frac { 2 }{ 3 } src=https://huaweicloudobs.ahjxjy.cn/F7BE9659ED2B1AE2CF628D7EF81508DB.png style=vertical-align: middle;/>