All of them felt it necessary that they the meeting.
A. attend
Bwould have attended
C. attended
Dwere to attend
网友回答
(答案→)A. attend
B. would have attended
C. attended
D. were to attend
解析：考查从句中的虚拟语气。句意：他们所有的人都认为参加会议室必需的。根据句型It is/was necessary that + 主语 + （should） + v进行判定。题干中it作形式宾语，that引起真正地宾语从句，从句中应使用上述句型中主语从句的should + v结构，其中should可以省略。此类试题往往是考试的焦点，因为学生往往忽略should的省略，虽然省略了，但其后的动词原形不变。故A正确。