问题补充：
Had it not been for the doctors careful treatment ,he couldn have lived till last year 的语法分
答案：
如果没有医生仔细的治疗,他不能活到去年.
======以下答案可供参考======
供参考答案1:
Had it not been ... 是倒装的虚拟条件句，相当于 If it had not been ...
虚拟条件从句中如果有 had, were, should，可省略 if，并将它们提到主语之前，从而构成倒装。
供参考答案2:
Had引导的条件状语,如果....,这类句子主要见于外国的文学刊物里,增加语言的多样性,其实结构非常简单,看到这种句子就把had换成if,if it is not for the doctors careful treatment, he couldn have lived till last year.这样就好理解了
另外后面半句运用了虚拟语气,因为整个句子是假设的,在虚拟语气下,can have done something变为couldn have been,是不可能做某事的意思
