问题
选择题
| 如图所示，A、B两物体叠放在一起，以相同的初速度上抛(不计空气阻力)，下列说法正确的是（ ） |
|
A．在上升和下降过程中A物体对B物体的压力一定为零 B．上升过程中A物体对B物体的压力大于A物体受到的重力 C．下降过程中A物体对B物体的压力大于A物体受到的重力 D．在上升和下降过程中A物体对B物体的压力等于A物体受到的重力 |
答案
答案：A
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| 如图所示，A、B两物体叠放在一起，以相同的初速度上抛(不计空气阻力)，下列说法正确的是（ ） |
|
A．在上升和下降过程中A物体对B物体的压力一定为零 B．上升过程中A物体对B物体的压力大于A物体受到的重力 C．下降过程中A物体对B物体的压力大于A物体受到的重力 D．在上升和下降过程中A物体对B物体的压力等于A物体受到的重力 |
答案：A
| 用方框中所给单词的适当形式填空，使短文正确、通顺。每词限用一次。 | |
to the moon. When you 2________ water, it is easy for you to climb big rocks, because you are no longer 3________. Here, under water, everything is blue and 4________. During the day, there is much light. When fish swim nearby, you can 5________ them with your hands. When you have tanks (罐) of air on your 6________ you can stay in deep water for a long time. But you must be 7________ when you dive in deep water. To catch fish is one of the most interesting 8________ of this sport. Besides, there are more uses for skin-diving. You can 9________ ships without taking them out of water. You can get 10________ things from the deep water. Now you see skin-diving is both useful and interesting. |