It has been said that “happiness is like a butterfly, which, when________ , is always beyond our grasp, but which, if you will sit down quietly, may alight upon you.” (pursue)
| A．pursuing | B．pursued |
| C．to pursue | D．having pursued |
— It’s a long time ______I saw you last.
— And what is a pity now that it will be a long time______ we see each other again.
| A．before; since | B．since; when |
| C．when; before | D．since; before |
So quickly is science and technology advancing ______ is a possibility today may be a reality tomorrow.
| A．that what | B．which | C．what | D．that which |
With the widespread of fog and haze(雾霾) in central and eastern China, our government is supposed to ______ their efforts to prevent further pollution.
| A．make up | B．show up |
| C．step up | D．wake up |
The Yeti is said to be a large, hairy animal walking _____two feet like a human being and moving _____ amazing speed and strength.
| A．with; at | B．by; at |
| C．on; with | D．on; at |
— Could you meet me at the airport?
— I'd like to，but I'm afraid I ______ a very important meeting when you return.
| A．am attending | B．was attending |
| C．will be attending | D．will have attended |