Question

____,he often helps me with my study

____,he often helps me with my study
A however he is busy
B however busy is he
C no matter he is busy
D no matter how busy he is
为什么答案是D？ABC哪错了？no matter how不就等于however么？

Answer 1

中文意思相同，但是：
no matter how 只能引导状语从句
however 既可以引导状语从句，也可以引导名词性从句。

这道题是状语从句，所以不能用however
判断到底属于哪种类型的从句也很简单，看看句子里面有没有逗号（插入语除外）
有逗号就是状从，没有逗号就是名词性从句

希望对你有所帮助，不懂的话可继续追问

Answer 2

no matter how和however是不一样的
前者是如论多（忙啊或者啥），后者是然而，无论如何的意思
加到句子翻译里，正确答案就出来了。