$\frac{3}{4}$ ×16=         1-0.65=         74÷1000=       150×0.06=

18÷ $\frac{2}{3}$ =         0.9+4.08=        $\frac{6}{7}$ - $\frac{1}{4}$ =         200×39=

4×5÷4×5=      1÷0.25=        0.04²=           13.2×25×0.4=

一汽车在平直公路上行驶，其位移x（m）随时间t（s）变化的规律为：x=25t﹣ $\frac{5}{2}$ t²，则汽车行驶3s后速度为____ m/s，5s内汽车位移为____ m．

根据下列短文，选择最佳选项。

    Sam likes soccer. He always watches soccer games on TV. His wife (妻子) Nina likes watching TV plays (电视剧). One evening at 7:00, Sam watches an interesting soccer game on TV. The TV also has a good TV play. It is Nina's favorite. She wants to watch it very much, but Sam sits before (在……之前) the TV. He doesn't let Nina watch the TV play. Nina is not happy, so she goes to her mother's home at 7:30 in the evening. When she comes into her mother's home, her father watches that soccer game, too.     

     “Where is my mother, Dad?”asks Nina.

     “She goes to your grandma's home,”says her father.

     “Why?”

     “I want to watch the soccer game, but she likes to watch a TV play.”

我国实行的基本经济制度是：以____为主体，____经济共同发展。