It was 80 years before Christopher Columbus crossed the Atlantic _____ Zheng He had sailed to East Africa.
| A．when |
| B．that |
| C．after |
| D．since |
—The plane is due to take off at 7：50 from the airport.
—________ we fail to arrive there on time?
—Try to take another flight then.
| A．What if | B．As if |
| C．Even if | D．Only if |
The traditional view is ________ we sleep because our brain is “programmed” to make us do so.
| A．when | B．why | C．whether | D．that |
The door burst open and ________，shouting with anger.
| A．in rushed the crowd | B．rushed in the crowd |
| C．the crowd in rushed | D．in the crowd rushed |
Fog ________ the train timetable.
| A．upset | B．upsetted |
| C．was upset | D．was upsetting |
________ we go swimming every day ________ us a lot of good.
| A．If；do | B．That；do |
| C．If；does | D．That；does |