Only after he realized the significance of mastering two languages __________ English carefully.
| A．did he set about learning | B．did he set out learning |
| C．had he set about learning | D．had he set out learning |
—Why do you choose to work in an international travel agency?
—Well，you know，English is my ________，so it is my best choice.
| A．strength |
| B．talent |
| C．ability |
| D．skill |
The idea for the new plan came to his mind，________ to his experiment in the lab.
| A．while devoting |
| B．while devoting himself |
| C．while he was devoted |
| D．while devoted |
Your understanding on the theory is________satisfactory. You must read more after class.
| A．far from |
| B．up to |
| C．along with |
| D．free of |
Not until they left school________ how much their teachers loved them and helped them.
| A．they realized |
| B．did they realize |
| C．they would realize |
| D．had they realized |
I thought Peter would have helped you.________is a great pity that he should be so selfish.
| A．Which |
| B．It |
| C．What |
| D．As |