【题目】The chairman thought ________ necessary to invite Professor Smith to speak at the meeting.
A.that
B.it
C.this
D.him

【答案】B
【解析】句意：主席认为邀请史密斯教授在会上讲话很有必要。考查it的用法。本句用it作形式宾语，代替 to invite Professor Smith to speak at the meeting，其他选项均不可以充当形式宾语。所以答案是B。