The city was difficult , was defended by an army of 6,000 men.
A. to be taken; which
B. to take; that
C. to take; which
D. to be taken; that
网友回答
A. to be taken; which
B. to take; that
(答案→)C. to take; which
D. to be taken; that
解析： The city was difficult to take = It was difficult to take the city. 只要这两种句型能够互换，不定式就得用主动的形式。