We were stuck at the airport because of the heavy fog, otherwise we ________ here in time for the conference.
| A．arrived | B．had arrived |
| C．would arrive | D．would have arrived |
We observed some young men __________into the building at 11：00 last night.
| A．to slip | B．slipped |
| C．slipping | D．being slipped |
Hangzhou is __________beautiful city，and it is worth__________.
| A．a most；visiting | B．the most；to visit |
| C．a most；to visit | D．the most；visiting |
The boy is old enough to __________the difference ________right and wrong.
| A．speak; from | B．tell; between |
| C．say; of | D．judge; from |
He fell in love__________Mary and asked her to marry__________him.
| A．to；with | B．with；to |
| C．with；with | D．with；/ |
We laugh at jokes, but seldom __________about how they work.
| A．we think | B．think we |
| C．we do think | D．do we think |