The factory ____ the students visited last week is the one ____ I have worked for thee years．
| A．that; which | B．when; in which |
| C．/; where | D．which; that |
Hurry up, or the tickets ________out by the time we get there.
| A．will have sold | B．will sell | C．have sold | D．will have been sold |
As we came to the work site, the workers were seen _______the new house.
| A．building | B．build | C．built | D．to build |
. The reason for all the changes being made _______to us yet.
| A．has not explained | B．has not been explained |
| C．did not explained | D．were not explained |
24. You ought to have put the milk in the refrigerator, and now ________sour.
| A．it smell | B．it is smelt | C．it smells | D．it is smelling |
Tim ________since he lost his job three weeks ago.
| A．had been unemployed | B．was unemployed |
| C．has been unemployed | D．has unemployed |