For weeks, the street hasn’t been cleaned by the cleaners, _______makes it very dirty.
| A．who | B．which | C．that | D．this |
Due to bad weather we have to put ___ off until next week to go camping in the mountains．
| A．it | B．that | C．one | D．this |
—Do you know how to start the machine?
—________．I’m a green hand．
| A．Not a clue | B．Exactly | C．By all means | D．Just so-so |
We are a team so we must assist one another _____ completing the task．
| A．with | B．to | C．at | D．in |
—Excuse me, Madam．Taking photos is forbidden here out of security．
—I’m really sorry, I _______ of that．
| A．am not informed | B．hasn’t been informed |
| C．hadn’t been informed | D．wasn’t informed |
The civil war broke out in Libya, ______ to the instability of the international oil price．
| A．to contribute | B．contributed |
| C．having contributed | D．contributing |