—We all had a lot of fun at the barbecue yesterday．Pity you weren’t there.
—I really should have gone with you but I _____ on some remaining problems.
| A．worked | B．was working |
| C．would work | D．would have worked |
__________ time went by, we grew older.
| A．As | B．With | C．When | D．While |
English __________ in our school for almost 60 years.
| A．has taught | B．was taught | C．had been taught | D．has been taught |
Look at this! It’s broken now! You __________ have been careful!
| A．could | B．must | C．would | D．should |
It took seven years __________ they finally got married.
| A．since | B．after | C．before | D．when |
— Where is the panda?
— It __________ by the doctor now.
| A．was being examined | B．is being examined |
| C．will be examined | D．has been examined |