问题
选择题
It is strongly recommended that the machine_____________ every year.
A．are checked
B．should check
C．checked
D．be checked
答案
答案：D
题目分析：It + be + recommended + that从句结构中，that从句应用“ should + 动词原形”，其中should可省略,故选D。
点评：It + be + 动词的过去分词 + that从句ordered, suggested ,advised, requested, demanded, advised , required , insisted…)，that从句应用“ should + 动词原形”，其中should可省略的虚拟语气。