______ it have been the failure to pick up directions from the ground control that caused the air crash?
| A．Must | B．Could | C．Would | D．Should |
Our teachers do believe that all the students in our school will do well in the coming college entrance examination, _______?
| A．don’t they | B．will they | C．won’t they | D．do they |
—So when did you meet Joan?
—It was last Sunday _______ she came to visit my sister.
| A．that | B．since | C．when | D．Before |
—What do you think of Mrs. Smith?
—She is _______ of a good housewife, for her children’s room is always a terrible mess.
| A．nobody | B．somebody | C．something | D．nothing |
—Would you like to join us in the barbecue this Friday afternoon?
—Sorry, _______.
| A．I’d love to | B．I’ll be tied up then | C．it all depends | D．I’m not interested |
The charity sale our school organizes every year has taught us much. _______ we would never have learned it in class.
| A．Therefore | B．Meanwhile | C．Otherwise | D．Instead |