I first met Tom 10 years ago. He ______ in a radio factory at that time.
| A．had worked | B．has worked |
| C．was working | D．has been working |
____some doubt among scientists about the cause of cancer.
| A．It exists | B．There exists | C．There is existing | D．It is existing |
---Try not to work yourself too hard. Take it easy.
--- Thanks. _________
| A．So what? | B．No way | C．What for? | D．You， too. |
The Harry Potter books are quite popular; they are in greatin this city.
| A． | quantity | B． | progress | C． | production | D． | demand |
The manager ______ the workers how to improve the program since 9 am.
| A．has told | B．is telling | C．has been telling | D．will have told |
I'm going to Europe on vacation together with John if Ifind the money.
| A． | can | B． | might | C． | would | D． | need |