___David says sounds right to Helen.That's why she has made up her mind not to leave him ___happens

这两个单词意思都一样,都是无论什么的意思
但no matter what只能放在句首,在句中,只能用whatever
"no matter +疑问词" 或"疑问词+后缀ever" .
例如：
No matter what happened,he would not mind.=Whatever happened,he would not mind.
不管发生什么,他不在意.
替换：
no matter what = whatever
no matter who = whoever
no matter when = whenever
no matter where = wherever
no matter which = whichever
no matter how = however
注意：no matter 不能引导主语从句和宾语从句.
(错）No matter what you say is of no use now.（对）Whatever you say is of no use now.你现在说什么也没用了.（Whatever you say是主语从句）
（错）*ers have to eat no matter what they're given.
（对）*ers have to eat whatever they're given.囚犯们只能给什么吃什么.你没看我回答的后面说的吗？no matter 不能引导主语从句和宾语从句。 (错）No matter what you say is of no use now.（对）Whatever you say is of no use now. 你现在说什么也没用了。（Whatever you say是主语从句） ___David says sounds right to Helen.这个句子的意思是无论大卫说什么，海伦都觉得对。这是个主语从句。所以不能用NO matter。