1 . 他突然意识到照片中的其他中国人不关心他们的同胞发生了什么事情。（运用it作形式主语）
______________________ the other Chinese men in the photo apparently did not care about what was happening to their fellow countrymen.

3 . Light pollution not only damages our vision health but also makes __________ difficult for us to sleep at night. (用适当的词填空)

4 . 令人惊喜的是，直到20世纪70年代，现代人才有人知道它们。
________________ no one in modern times knew about them until the 1970s.

6 . __________is not unusual to see American university students drive to school every day. (用适当的词填空)

8 . ________ is important to learn English well.

A．This

B．Who

C．It

D．Which

9 . 但是在网上花太多时间是不健康的，并且很难集中精力在生活中的其他事情上。
But __________ too much time online __________ and makes it __________ other things in life.

10 . 对于你们这一代青少年来说，喜欢电脑游戏和网络世界并不罕见。
It is __________ for teenagers of your generation __________ computer games and the online world.