骑自行车的人，上坡前要加紧蹬几下脚踏板，这样做的目的是( )

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A：增大车子的惯性

B：增大车子向前的牵引力

C：增大车子的动能

D：增大车子的势能

上一题下一题 0.0难度选择题更新时间:2019-01-12 06:46:18

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C

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    Come and see the India elephants and the new tigers from America. The bears are waiting to meet you, and the monkeys from China are waiting to throw（扔） things to you. The lovely dogs from Australia are waiting to laugh at you. The giraffes from Brazil are waiting to look down on you.
Tickets                             Open time
Grown-up:（成人）$2.00             9:00a.m—4:00p.m
Children :over 12 $1.00               Except（除）Friday
Under12 Free(免票)                  10:00a.m—3:00p.m
Keep the zoo clean!
Don't touch(触摸) , give good food or go near the animals!

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