Our teacher insisted that the key words worth paying attention before class.
A. be underlined
B. being underlined
C. to be underlined
D. to being underlined
网友回答
A. be underlined
B. being underlined
(答案→)C. to be underlined
D. to being underlined
解析：考查虚拟语气。to是与pay attention连在一块的；(should)be underlined是insist的虚拟语气，故选C。