题干

如图中a、b是两个位于固定斜面上的正方形物块,它们的质量相等。F是沿水平方向作用于a上的外力。已知a、b的接触面,a、b与斜面的接触面都是光滑的。正确的说法是   (    )

A:a、b一定沿斜面向上运动

B:a对b的作用力沿水平方向

C:a、b对斜面的正压力相等

D:a受到的合力沿水平方向的分力等于b受到的合力沿水平方向的分力

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D

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    Children like to imagine they are someone else in a game. As a parent you might never guess how it can benefit your child. It helps your child:

Develop Social Skills

    As children play pretend games, they explore relationships between family members, friends and coworkers and learn more about how people interact. Playing doctor, they imagine how physicians care for their patients. Imaginative play helps of a game or to lose a pet, they are better able to help those in need. They become more willing to play fair, to share, and to cooperate.

Build Self-confidence

    Children have very little control over their lives. Imagining oneself as a builder of skyscrapers or a super hero defending the planet is inspiring to children. It helps them develop confidence in their abilities and their potential.

Promote Intellectual Growth

    Using imagination is the beginning of abstract thought. Children who can see a king's castle in a mound of sand or a delicious dinner in a mud pie are learning to think symbolically(象征性地). This skill is important in school where a child will have to learn that numbers symbolize groups of objects, letters symbolize sounds, and so on.

Practice Language Skills

    Kids who pretend with their friends do a lot of talking. This helps increase their vocabulary, improve sentence structure and develop communication skills.

Get Rid of Fears

    Pretending can help children get rid of their fears and worries. When children role-play the big, bad monsters under the bed, they gain a sense of control over him and he doesn't seem quite so big or so bad.