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
While the police have already done a lot of investigation, much evidence ___ __.
A．is remaining to be confirmed B．remained to be confirmed
C．is remained to be confirmed D．remains to be confirmed
_____ on everyday practice, progress in English is a goal which can be achieved．
A．Based B．Basing C．Having based D．Being based
Look out! Keep away from the house, _____ the roof is under repair．
A．whose B．which C．of which D．where
．You'd better get the problem solved as soon as possible ______ it becomes out of control．
A．when B．before C．since D．unless
