Sex education is a sensitive area for some parents, and thus it should remain _________.
| A．random | B．previous | C．optional | D．vital |
The shopkeeper didn’t want to sell for __he thought was not enough .
A where B. how C. what D. which
The place __ the bridge is supposed to be built should be ____the cross-river traffic is the heaviest .
| A．which; where | B．at which ;which |
| C．at which ;where | D．which ;in which |
Mary wrote an article on ____the team had failed to win the game .
| A．why | B．what | C．who | D．that |
After Yang Liwei succeeded in circling the earth ,___our astronauts desire to do is walk in space .
| A．where | B．what | C．that | D．How |
we can not figure out ____quit a number of insects ,birds ,and animals are dying out .
| A．that | B．as | C．why | D．when |