Question

5．他与疾病作顽强斗争很勇敢．
It is braveof him to fightagainst the disease．

Answer 1

分析 of him to fight．

解答 答案：of him to fight．结合句意是表达某人做某事是怎样的用句型It's+adj+of sb+to do sth，与…斗争结合against用fight against，故答案是of him to fight．

点评 It's+adj．+for sb．+to do（ sth．） 与 It's+adj．+of sb．+to do（ sth．）的区别
用of 的话，adj就用来形容sb的．即形容词是描述不定式行为者的性格、品质的，如kind，good，nice，right，wrong，clever，careless，polite，foolish等，用of sb..故可以换成 sb is adj to do 
比如：it‘s nice of you to help me．=you are nice to help me．
1 It's very kind of you to help me．你能帮我，真好．
2 It's clever of you to work out the maths problem．你真聪明，解出了这道数学题．
用for 是因为前面的adj是来描述do后面的sth．即形容词仅仅是描述事物，不是对不定式行为者的品格进行评价，用for sb．，这类形容词有difficult，easy，hard，important，dangerous，（im）possible等．如 
1 It's very dangerous for children to cross the busy street．
对孩子们来说，穿过繁忙的街道很危险．