单选题 It is generally thought to be of importance to a man that he ______ himself.
A. knew B. know C. knows D. must know

【正确答案】 B

【答案解析】[解析] 本题的答案主要决定于It is of importance that...=It is very important that...，在这个句式中that从句谓语需用虚拟语气(should)+动词原形。