118.Greater efforts to control the population must be made if food shortage __________ avoided.

问题描述:

118.Greater efforts to control the population must be made if food shortage __________ avoided.
A.is to be
B.can be
C.will be
D.has been
is to be

将来时的被动语态
如果要避免粮食短缺,就一定要付出更大的努力来控制人口.