问题补充：
The elderly should politely. Also, they must well.
A. speak, take care of
B. be spoken, be taken care
C. be spoken to, be looked after
D. be spoken to, be taken care of
答案：
A. speak, take care of
B. be spoken, be taken care
(答案→)C. be spoken to, be looked after
D. be spoken to, be taken care of
解析：此题重点考查含有情态动词的被动语态的基本构成。
