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问题 多项选择题

膨胀土路堑开挖时要注意的事项有( )。

A．先开挖路堑，再施工截、排水设施，将水引至路幅以外

B．挖方边坡不要一次挖到设计线

C．沿边坡预留一层土，待路堑挖完时，再削去边坡预留部分

D．修整后的边坡应立即浆砌护坡封闭

E．修整后的边坡应立即植草

答案

参考答案：B,C,E

填空题

根据首字母或汉语提示填空。

1．Many students find it very difficult to m            English words.

2．Lucy can write English very well, but she must pay attention to her p            and try to speak it better.

3．Just now I r            that I had left my schoolbag on the playground.

4．This exam is a real c           . Please study hard for it.

5．Although I failed four times, my father encouraged me to have a f            try.

6．In my d            life, reading newspapers has become a part of mine.

7．He used to be a "problem child", but recent c            changed his life.

8．Our teacher listed three p            on how to write a good essay.

9．Luckily, she has an o            to make an advanced study in Beijing.

10．Most children can not c            on one thing for a long time.
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多选题

一升降机在箱底装有若干个弹簧，设在某次事故中，升降机吊索在空中断裂，忽略摩擦力，则升降机在从弹簧下端触地后直到最低点的一段运动过程中（　　）

A．升降机的速度不断减小

B．升降机的加速度不断变大

C．先是弹力做的负功小于重力做的正功，然后是弹力做的负功大于重力做的正功

D．到最低点时，升降机加速度的值一定大于重力加速度的值
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