接触电压与跨步电压的大小皆与接地网的电位有关。（）

两组对边分别平行的四边形，叫作（    ），只有一组对边平行的四边形叫作（    ）。

Rewrite the following sentences as required.

小题1:The medicine has a good effect on the illness. (一般疑问句)

_______________ the medicine _______________ a good effect on the illness?

小题2:He will be responsible for the new project. (反意疑问句)

He will be responsible for the new project, _______________ _______________?

小题3:Jimmy promised to work harder in English than before. (划线提问)

_______________ did Jimmy promise to _______________?

小题4:The detective discovered some important clues for the case. (被动语态)

Some important clues for the case _______________ _______________ by the detective.

小题5:There was something wrong with the machine as soon as the engineer left. (保持句意)

The machine _______________ _______________ as soon as the engineer left.

小题6:Will they have a discussion after class? He wanted to know. (合并一句)

He wanted to know _______________ they _______________ have a discussion after class.

小题7:for, used to, and, breakfast, have, milk, I, bread (连词成句)

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（四）某港区二号泊位将装卸一艘四个舱的船舶。各舱船吊生产率为20吨/台时，同时配备一台台时效率为35吨/台时的门机，以平衡各舱装卸作业时间。门机与船吊在同一舱工作时互不干扰，各舱货量分别为一舱1000吨、二舱1800吨、三舱1500吨、四舱1600吨。请回答下列问题：

按机械生产率计算的全船最短作业时间为（ ）小时。

A．51.30

B．51.58

C．52.30

D．53.10

在订立合同时一方哪些行为可导致合同的可撤销（）。

A、有欺诈行为

B、有乘人之危的做法

C、对合同内容有重大误解

D、有使合同内容显失公平的做法

时效中断