根据《水利工程建设项目档案管理规定》的有关规定，水利工程档案

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问题单项选择题

根据《水利工程建设项目档案管理规定》的有关规定，水利工程档案的保管期限分为( )。

A．永久、长期、短期三种

B．长期、中期、短期三种

C．长期、短期两种

D．永久、临时两种

答案

参考答案：A

填空题

用延续性动词改写下列句子。

1. The man has left China. The man has _____ _____ _____ China for 20 years.

2. The movie has finished. The movie has _____ _____ for half an hour.

3. I have borrowed the book. I have _____ the book for a month.

4. He has joined the Party. He has _____ _____ the Party for 30 years.

5. I have bought the bike. I have _____ the bike for 6 years.

问答题

三个带正电的粒子a、b、c（不计重力）以相同的动量水平射入正交电磁场中，轨迹如图所示，则可知它们的质量m_a、m_b、m_c的大小次序为______，三个粒子中动能增加的是______粒子．