根据下列语句，分别设适当的未知数，列出二元一次方程或方程组：

（1）甲数的$\frac{3}{2}$比乙数的2倍少7；

（2）摩托车的时速是货车的$\frac{5}{3}$倍，它们的速度之和是150．

“a<1”是 “$\frac{1}{a}>1$”的（   ）条件

试回答以下问题：

根据短文理解, 从A、B、C、D四个选项中选择正确答案填空。

    Mr. Smith 1 from London. Now he is in China. He is 2. He teaches 3 a middle school. He works very hard. His students like 4 very much. He can 5 a little Chinese. His students often teaches him Chinese 6 Sundays. Mr. Smith likes playing football. He often plays football 7 his students.

    Mr. Smith 8 a son. His name is Jack. He is student. He studies in a middle school. He goes to school 9 bike everyday. He gets back home at four in the afternoon. He likes 10 TV in the evening.

    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.