For years, it was viewed as a serious problem, ________ that has never been really solved.
| A．one | B．where | C．it | D．which |
The world today _____ different without the amazing discoveries produced by great scientists.
| A．were | B．had been | C．would be | D．would have been |
I was surprised to find the snack shops around the school empty; the students everything!
| A．had been buying | B．had bought |
| C．have bought | D．have been buying |
The driver suggested that we set out before seven in the morning in order to avoid traffic jams.
| A．should | B．might | C．could | D．would |
—I’m sorry I have no cash in hand.
—. I’ll pay for everything.
| A．Take your time | B．You’re right |
| C．Whatever you say | D．Take it easy |
According to the weather forecast, this airport will not be suitable for landing, and 50 miles away.
| A．nor the one will | B．nor will the one |
| C．so the one will | D．so will the one |