be动词后面不可以跟实意动词，study是实意动词，所以不可以说it is study。这句话里，只有hard是形容词，所以，用形式主语的话，只有It's very hard这一种方式。him不可以变成he，因为he是主语代词，放在for后面，自然要用到宾格形式。以上是对你问题的分析。这句话如果换一种说法，可以是：Study two languages is very hard for him.或者For him, study two languages is very hard....
你好。1 It's very hard for him to study two languages. ------正确
To study two languages (at the same time) is hard for him ------正确 2for是介词，所以，介词 + 宾格代词。...
