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问题 单项选择题

柱锤冲扩桩施工时，下述（）不正确。

A.柱锤直径宜为300～500mm；长度宜为2～6m；质量宜为1～8t 

B.采用柱锤冲击成孔较困难时，可采用长螺旋钻机成孔 

C.成孔时如产生缩径或坍孔时，可采用填料冲击成孔法 

D.每个桩孔应夯填至桩顶设计标高以上至少0.5m

答案

参考答案：B

问答题

如图所示，蜡烛经凸透镜成清晰的像在光屏上，请画出入射光线ab经透镜后的出射光线，并确定透镜焦点的位置（保留作图过程）．
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单项选择题


Directions: There are 10 blanks in the following passage. For each numbered blank, there are four choices marked A, B, C and D. Choose the best one and mark your answer on the ANSWER SHEET with a single line through the center.

Our planet is like a bit spaceship. Our atmosphere acts (51) a shield against harmful radiation and space debris. (52) holds the air and people on the spaceship, (53) everything doesn’t float away. Each of us is an astronaut and our spaceship, the earth, provides our food and water. The sun is our energy (54) and without it we would not be able to survive.
(55) every spaceship, the earth is a closed system. The only thing we receive from the outside is energy from the sun. Everything else must be used (56) again. We astronauts don’t seem to realize that this spaceship is the (57) one we’ve got. We (58) its resources and waste the energy the plants have stored from the sun. If we (59) our spaceship, we will destroy ourselves as well. Maybe if we look at the universe which surrounds us, we will appreciate our own spaceship more and take (60) care of it.

A．abuse

B．utilize

C．adjust

D．accumulate
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