Whenever I met him, _____ was fairly often, I like his sweet and hopeful smile.
| A．what | B．that | C．which | D．when |
I had hardly got to the office________my wife phoned me to go back home at once.
| A．when |
| B．than |
| C．until |
| D．after |
Please call my secretary to arrange a meeting this afternoon，or________it is convenient to you.
| A．whenever |
| B．however |
| C．whichever |
| D．wherever |
He was so deep in thought，thinking of the problem ________ he knocked into the tree without noticing it.
| A．when |
| B．while |
| C．because |
| D．that |
________you’ve experienced it，you can’t understand how I felt.
| A．Once |
| B．Because |
| C．Unless |
| D．While |
________ you may have，you should gather your courage to face the challenge.
| A．However a serious problem |
| B．What a serious problem |
| C．However serious a problem |
| D．What serious a problem |