问题补充:
Tom thought it was an honor to speak in the ceremony.
A. to invite
B. to be invited
C. inviting
D. having invited
答案:
A. to invite
(答案→)B. to be invited
C. inviting
D. having invited
解析:考查it充当形式主语。It是形式主语,Tom和invite构成被动的关系。to be invited to speak in the ceremony是真正的主语。句意:Tom认为被邀请在庆典上发言是一件光荣的事情。