15．We know it is hard to make such a decision____he has just built up the team for a year and the project is going through the important stage now.
| A．that | B．as | C．when | D．Before |
All plants need air_____ they need water.
| A．like | B．as if | C．as | D．so |
_____ he wasn’t ready in time, we went without him.
| A．Since | B．As | C．For | D．Because of |
Sit _____ you like.
| A．where | B．at the place | C．as | D．wherever |
I had hardly sat down_____ the telephone rang
| A．than | B．when | C．as | D．after |
I’ll tell him about it_____I see him.
| A．as soon as | B．so soon as | C．while | D．as |