题干

物体静止在一固定的斜面上,下列说法正确的是(    )

A:物体对斜面的压力和斜面对物体的支持力是一对平衡力

B:物体对斜面的摩擦力和斜面对物体的摩擦力是一对作用力与反作用力

C:物体所受重力和斜面对物体的作用力是一对作用力和反作用力

D:物体所受重力可以分解为沿斜面的力和对斜面的压力

上一题 下一题 0.0难度 选择题 更新时间:2018-08-19 06:31:33

答案(点此获取答案解析)

B

同类题5

根据短文内容, 从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Let children learn to judge their work.____.If corrected too much,he will stop talking.

    He notices a thousand times a day the difference between the language he uses and the language those around him use.Bit by bit,he makes the necessary changes to make his language like other people's.____.They learn to do without being taught to walk,run,climb,whistle,ride a bicycle.They compare their own performances with those of more skilled people,and slowly make the needed changes.

    But in school we never give a child a chance to find out his mistakes and correct them for himself.We do it all for him.____.Let him work out,with the help of other children if he wants,what this word says,what the answer is to that problem,and whether this is a good way of saying or doing this or not.

    If it is a matter of right answer,as it may be in mathematics or science,give him the answer book.____.Why should we teachers waste time on such routine work?____.Let the children learn what all educated people must some day learn,how to measure their own understanding,and how to know what they know or do not know.

A.Children learn to do all the other things in the same way.

B.Let him correct his own papers.

C.Point out his mistakes.

D.We act as if we thought that he would never notice a mistake unless it was pointed out to him,or correct it unless he was made to.

E.We allow him to learn from other children.

F.A child learning to talk does not learn by being corrected all the time.

G.Our job should be to help the child when he tells us that he can't find the way to get the right answer.