含羞草受到接触时，开展的叶片会合持续，这种现象体现了生物的哪一个基本特征（    ）

   Today more and more cars go into families. Which car is the best for people? Different people have different ideas.
   Some people like the bright colour car made in China. It's really a good choice(选择). The bright colour car made in China is cheap, nice and safe. This kind of cars is suit for(适合于) the general income (收入一般的) family.
   Some people love famous foreign cars like Japanese cars, American cars and German cars. They're good but too expensive. But most people think famous foreign cars of better quality are better in safety. These are suit for the high income family or for business.
Some people like sports cars, because they're fast and exciting. Some sports cars are very nice but very expensive. Only rich people can afford them.
   Some people like travelling, so they need a travel car. Travel cars are comfortable. But they use much oil(油). What's the best car for us? Maybe it's a new and popular topic in life.

建国初期为巩固新生的人民政权而进行的斗争有（　　）

①和平解放西藏 ②稳定物价之战 ③土地改革运动 ④抗美援朝

竖直弹簧下端固定于水平地面上，如图所示，小球从弹簧的正上方高为h的地方自由下落到弹簧上端，经几次反弹以后小球最终在弹簧上静止于某一点A处，则（   ）