The number of air crashes that ________in developing countries ________increasing. [ ]

In order _______ his English，he joined an English club.

I wonder if you can look after yourself well.— . I’m not a child any longer.

－It’s difficult for village children to cross the river to school.－I think a bridge _________ over the river.

Tony ____ for the company as an engineer for twodecades. Now he teaches mechanics m Peking University.