We will cause less pollution _____________we can find ways to reuse or recycle more rubbish．（ ）
A．unlessB．ifC．though
Be quick, we’ll be late for the meeting.
| A．and | B．but |
| C．so | D．or |
I still remember my first teacher __________ we haven’t seen each other for many years.
| A．for | B．because |
| C．since | D．Though |
They have been friends __________ they were at primary school.
| A．before | B．as soon as |
| C．since | D．when |
I’ll go to visit my uncle in England ________ the winter holidays start.
| A．while | B．since |
| C．until | D．as soon as |
The mobile phone has changed people’s life a lot ________ it was invented.
| A．until | B．since |
| C．before | D．after |