I was on the highway when this car went past followed by a police car. They ______ at least 150 km an hour.
| A．should have been doing | B．must have been doing |
| C．could have done | D．would have done |
Everyone has periods in their lives________ everything seems very hard.
| A．when | B．where | C．which | D．That |
—How about camping this weekend，just for a change?
—OK，________you want.
| A．whichever | B．however | C．whatever | D．Whoever |
In _________to being used in industry，laser can be applied to operations in the hospital.
| A．devotion | B．addition |
| C．application | D．Reception |
Children under 18 will not be ____into the pub in this country.
| A．designed | B．decorated |
| C．competed | D．Admitted |
No one knows when such a custom first _____.
| A．came into power | B．came into being |
| C．came true | D．came out |