单选题 It was recommended that passengers ______ smoke during the flight.
A. not B. need not C. could not D. would not

【正确答案】 A
【答案解析】该题考查非真实条件从句中的虚拟语气的用法。在句型It is(was) recommended that…中，从句用虚拟语气，谓语动词形式为“should+动词原形”，其中should可以省略。