We haven't met for years，but we still ________greetings by email on festivals.
| A．change |
| B．replace |
| C．exchange |
| D．transfer |
They talked for about an hour of things and persons _____ they remembered in the school.
| A．which | B．that | C．who | D．whom |
Don’t be in a hurry. We are supposed ____________ this problem step by step.
| A．solving | B．to solving | C．to solve | D．solve |
_________you have a rich knowledge of Chinese history, try acting as a guide for these foreign visitors.
| A．Unless | B．Though | C．Now that | D．Ever since |
The school ______ my sister studies at is far from here.
| A．where | B．that | C．at which | D．in which |
You will succeed in the end _____________ you give up halfway.
| A．if | B．unless | C．now that | D．Until |