I don’t think ______ 18-year-old boy is serious enough to drive.

What do you think of haze(雾霾)？ —- It ____ us we all must try to do something to stop the air pollution.

A computer does only what thinking people _________.

We don’t like people _______ talk too much but never do anything. [ ]

The population of China is much ______ than that of ________ country in Africa.