问题
选择题
在水平路面上做匀速直线运动的汽车，受力情况是（ ）
A．不受力的作用
B．只受重力的作用
C．只受到重力、支持力的作用
D．受到重力、支持力、牵引力、摩擦力的作用
答案
汽车受到重力支持力相平衡，牵引力与摩擦力相平衡．
故选D．
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在水平路面上做匀速直线运动的汽车，受力情况是（ ）
A．不受力的作用
B．只受重力的作用
C．只受到重力、支持力的作用
D．受到重力、支持力、牵引力、摩擦力的作用
汽车受到重力支持力相平衡，牵引力与摩擦力相平衡．
故选D．
| 先阅读短文，掌握其大意。然后从方框中所给的词中选出恰当的10个，并用其适当形式填空， 每个词限用一次。 | |
way of learning. Is this the 2.________ way for students to learn? Of course not. There is another way to learn. That's students can learn by themselves. For 3.________, if you can't remember something, you look at your book to 4.________ the answer. How to teach yourself? First, read something you are 5._________ in. Second, ask yourself questions. A clever student is usually 6._________at asking questions. Third, answer the questions by 7.________ hard. And sometimes asking 8.________ people is useful. If you keep doing 9.________ these for a long time. You're sure to have great 10.________ in your study. |