单选题 By next year it ______ necessary to double the production quota to keep up with market demands.
A. were
B. will be
C. has been
D. being

【正确答案】 B

【答案解析】高级问题空格内应填入单数形式的谓语动词。这里不需要分辨主动语态和被动语态，只要考虑时态。时态在大部分情况下都是解题的提示。看到有next year，这是不是一个有力的提示?
非谓语动词＞单复数＞主动语态与被动活态＞时态→参考“托业语法考点汇总”