亚洲资源、环境问题日益严重的根本原因是（    ）

— Mum, I don't quite understand the Chinese saying.

— Dear, don't worry. _______ the years go by, you will get to know it.

I will send you lots of Chinese stamps  __________   your album. （  ）

关于做匀速圆周运动的人造地球卫星，下列说法中正确的是（   ）

Hangzhou ____ ____ ____ the West Lake in the world.