【单选题】【消耗次数：1】
They can’t leave until they _________ their work .
①
did
②
are doing
③
have done
④
his done
参考答案：
复制
纠错
相关题目
【单选题】
They can’t leave until they _______ their work .
①
did
②
are doing
③
have done
④
his done
【单选题】
They can’t leave until they ___ their work.
①
did
②
are doing
③
have done
④
has done
【单选题】
8.They can’t leave until they ______ their work.
①
did
②
are doing
③
have done
④
has done
【单选题】
They have done things they ought_____.
①
not to do
②
not to be done
③
not to have done
④
not having done
【单选题】
Can anything be done to_________ the negative influence of some television programs?
①
accept
②
assume
③
avoid
④
alarm
【单选题】
28.Fool ____ Jane is, she could not have done such a thing.
①
who
②
as
③
that
④
like
【单选题】
I should think they have done it ________, to avoid paying you the money.
①
with purpose
②
on purpose
③
in purpose
④
to purpose
【判断题】
Given that they are fresh from the university, the young people have done a good job.
①
正确
②
错误
随机题目
【单选题】
关于PI控制器作用，下列观点正确的有（）
①
可使系统开环传函的型别提高，消除或减小稳态误差；
②
积分部分主要是用来改善系统动态性能的；
③
比例系数无论正负、大小如何变化，都不会影响系统稳定性；
④
只要应用PI控制规律，系统的稳态误差就为零。