I failed in the final examination last term and only then ________ the importance of studies.
| A．I realized | B．I had realized | C．did I realize | D．had I realized |
________on a clear day，far from the city crowds，the mountains give him a sense of peace.
| A．Walked | B．To walk |
| C．Having walked | D．When he is walking |
Drive ________until you come to the small town，which lies about 100 kilometers ________ London.
| A．north; to the east | B．north; east of |
| C．to north; east of | D．to north; in the east |
—What's that terrible noise?
—The neighbors ________ for a party.
| A．have prepared | B．are preparing |
| C．prepare | D．will prepare |
Every possible means ________ to prevent the air pollution，but the sky is still not very clear.
| A．were using | B．have used |
| C．has been used | D．was used |
I invited Joe and Linda to dinner，but ________ of them came.
| A．neither | B．either | C．none | D．both |