题干

小明学习了力的知识后,对静止在水平桌面上的文具盒来进行分析,下列说法正确的是(  )

A:文具盒对桌面压力的大小等于它所受重力的大小

B:文具盒对桌面的压力与桌面对它的支持力是平衡力

C:因为文具盒处于静止状态,所以它没有惯性

D:文具盒不会自动沿桌面滑动,是因为受到摩擦力

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答案(点此获取答案解析)

A

同类题5

阅读下面短文。从短文后各题所给的四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项。

    Mr Jackson was blind from birth. He owned a fruit 1 on a very busy street. 2 he was visually disabled, he ran his business pretty handsomely. He could see nothing and he could only 3 the things within his reach. 4 he was able to handle it and was content with everything he had.

    One day his son came to him. He told Mr Jackson in 5 that he read in the newspaper of a 6 who could operate on his eyes and allow him to see. The father and son traveled to the doctor and paid for the 7.

    After the operation, the doctor asked Mr Jackson, “What is the first thing you are 8 to see when I take the bandages off?” He replied, “I really want to see my beautiful 9 on my stand!”

    The doctor and the son 10 Mr Jackson down to the busy street where his fruit stand had been located for so many years. The doctor 11 unwrapped the bandages 12 he could lay his eyes on the beautiful fruit! Mr Jackson was so full of 13 that he could finally see his life's work—taking care of his fruit! After a few hours of 14 his beautiful fruit stand, he looked down the street both ways and saw there were quite a few fruit stands in both directions. He looked 15 the street and saw many other fruit stands. He spent so much time looking at other people's fruit stands and 16 the competition. Soon his own business 17.

    From Mr Jackson's failure, we should know that everyone is a 18 individual with different fingerprints, DNA and thinking. What we need to do is just be ourselves and 19 everyone else to be who they are. Mind our own business and we should never be afraid of 20.