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
Recently a new social issue has been brought to everyone's attention ___ __food additives are abused．
A．when B．whether C．that D．which
