根据括号内的汉语提示，完成句子(每空一词)。

1. We should take good care of             (自己) while our parents are away.

2. I am looking forward to             (收到) the letters from the children in Yushu disaster area.

3. Millions of football fans enjoy             (观看) the World Cup in South Africa this summer.

4. There are 56             (民族) in China.We are like a big family.

5. Low-carbon is a popular word nowadays. We should make a great contribution to             

    (保护) the environment.

6. Li Weikang is a top student in our school. He is             (被期望) to enter Huanggang High

    School this term.

下列说法正确的是（　　）

A．功率表示物体做功的快慢，所以做功时间越短功率越大

B．在相同的时间内做功越多，功率就越大

C．功率大的机械比功率小的机械做功一定多

D．有力作用在运动的物体上，力一定对物体做功