We should keep trying, and I think our efforts will finally _____.
| A．pay out | B．pay back | C．pay for | D．pay off |
--- Hey, Mary, your backpack looks nice. When did you buy it.
--- I ____ it for two weeks.
| A．had | B．bought | C．have had | D．have bought |
Why do you insist on buying a car ______ you have such good public transportation here?
| A．because | B．unless | C．when | D．though |
The owner still doesn’t know _______ broke into the house and stole the money.
| A．when it was that | B．who it was that | C．who was it that | D．when was it that |
The scientists have made an exhaustive study of the virus _______ many people have been inflected.
| A．to which | B．in which | C．with which | D．for which |
When I was in Spain last summer, I ______ quite a lot of Spanish.
| A．made up | B．picked up | C．gave up | D．took up |