_____you don’t lose heart, it will be easy for you to overcome the difficulties.
| A．As well as | B．So long as | C．So far as | D．As soon as |
Scientists say it may be five or ten years___________ it is possible to test this medicine on human patients.
| A．since | B．before | C．after | D．when |
Neither of them knew what_____ was doing.
| A．other | B．others | C．the other | D．another |
The murderer was brought in, with his hands _____behind his back.
| A．to be tied | B．being tied | C．tied | D．having tied |
--" Would you mind the window? It's hot here!" May said.
--"__________. "Tom replied.
| A．to open ; No, please | B．open ; Yes, please |
| C．opening; No, of course not | D．opening ; Yes, please |
--Hi, Tracy, you look tired.
--I am tired. I__________ the living-room all day.
| A．painted | B．have been painting |
| C．had painted | D．have painted |