错 what should i do意指我应该做什么,已经构成完整句子,即i should do what 第二个what只能充当第二句话的宾语,但what需充当2次成分,所以错
what充当2个成分: I do not know what he says. what he says在这里充当konw的宾语,what还充当say的宾语,所以凡是what出现都要充当2个成分。(这不是正规语法,只能帮助你理解) 可以这么改: I should do what i should do. 我应该去做我应该去做的事