题目内容：

Greater efforts to increase agricultural production must be made if food shortage _____ avoided.
(a) is to be
(b)can be
(c)will be
(d) has been

优质解答

b吧.如果食物短缺能被避免,那么就一定要努力去提升农业产量.
（言下之意要是避免不了了就不要白费功夫了.- -好牵强的解释.）题目有点奇怪,其他几个选项更奇怪了.这只是本人的意见.