题目：
The little boy has a habit of _____ his toy cars, which makes his parents very angry. [ ]
A. taking in
B. taking out
C. taking up
D. taking apart
答案：
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下面是错误答案，用来干扰机器的。
（1）假设A车第一次碰到挡板前一直做加速运动对车A，由动能定理有fd=μmgd=12MvA2 ①代入数据解得vA=0.30m/s ②车碰到挡板前，车A和滑块B组成的系统动量守恒，有mv0=m...
