---Why did he get up so early in the morning? --- He got up early in order that he could catch the early bus.

I hate travelling by air_______ you usually have to wait for hours before the plane takes off.

_______he is only 8 years old , he knows more about science than his father .

 —_____is your mother ? —A nurse. She works in a hospital. 

Rick has learned a lot about Chinese culture _____ he came to China.