_______ his return from America, he got down to his research.
| A．While | B．In | C．As | D．On |
It is well known that water is not _____ endless resource,nor _____ that can be made once more．
| A．the, / | B．an, one | C．an ．that | D．/, one |
---Mom．I’m so tired．I can’t walk any further．
---______, my dear．You can make it．
| A．Come on | B．No worry | C．That’s impossible | D．No problem |
A student will be immediately punished if he is foundin the exam.
| A．cheat | B．to cheat | C．cheated | D．cheating |
—Would you mind if I take the seat?
—.
| A．Yes, sit down, please | B．No, not at all |
| C．Surely, never mind | D．No, you can't take it |
The company plans tothe costs of raw materials by 10% next year.
| A．turn down | B．cut down | C．keep away | D．cut off |