搜题请搜索小程序“爱下问搜题”
问题 选择题

以下说法中正确的是（　　）

A．物体在平衡力作用下的运动过程中，机械能可能不守恒

B．物体在平衡力作用下的运动过程中，机械能一定守恒

C．物体克服重力做功时，机械能一定不守恒

D．物体如果受重力以外的力作用，机械能一定不守恒

答案

A、物体在平衡力作用下做匀速直线运动，若在水平方向做运动运动，机械能守恒，若在竖直方向做匀速运动，机械能不守恒，故A正确，B错误；

C、竖直上抛运动中，物体克服重力做功，机械能守恒，故C错误；

D、物体如果受重力以外的力作用，但其他力不做功时，机械能守恒，故D错误；

故选A

改错题
短文改错。

  Born to be the basketball player, Kobe Bryant 
 showed his shooting talent in an early age. He has always been
occupied with proving his skills on the court and improve himself.
Having been enjoyed a successful high school basketball
career, Kobe went straightly into the NBA after graduation.So
far, Kobe has led the Lakers to four NBA championship.
Therefore, he is never content with his past achievements. He
 is famous for getting his teammates stay up late practicing.
When he learned a new move, he asks his teammates to
practice it with her until it is perfect."When you win, you
have to constantly look for ways to get better."Kobe said.

1. _____
2. _____
3. _____
4. _____
5. _____
6. _____
7. _____
8. _____
9. _____
10. _____
查看答案
单项选择题

在汽车租赁合同中，出租人假若要在汽车租赁期间对汽车设定抵押权，必须满足的条件是( )。

A．承租人利益不受影响

B．承租人事先书面表示同意

C．承租人不再进行转租

D．出租人书面通知承租人
查看答案