I just wonder ________ that makes him so excited.
| A．why it does | B．what he does | C．how it is | D．what it is |
—Coach，can I continue with the training?
—Sorry，you can’t________you haven’t recovered from the knee injury.
| A．until |
| B．before |
| C．as |
| D．unless |
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 |