2道初中英语题,谢谢!No matter ____ difficult problems we meet, we won

No matter ____ difficult problems we meet,we won't fail unless we give up our hopes.这里用how还是what?为什么?
选what.因为what是连接代词,修饰名词problems
如果句子是：No matter ____ difficult the problems we meet,we won't fail unless we give up our hopes
选how.因为how是连接副词修饰形容词difficult
2.____ is like a small part of a machine.这里用we each还是each of us?为什么?
选each of us.因为系动词是is,主语就是单数each of us；而we each做主语是复数,需要用复数的谓语动词/系动词are.

1，用what因为后面是“困难的问题”是名词。what+名词
而how对形容词，副词提问 若用how,句子因为“how
difficult we meet ”
2，each of us
“we each”谓语要用复数“each of us”谓语用单数“
而这里的谓语是is 所以选”each of us“

第一个填what
no matter how 无论如何 后边一般接让步状语从句或者陈述句。
No matter how, however都可以引导让步状语从句， 同义，都表示“无论如何”的意思，又都引导让步状语从句，但有一些区别
no matter what 形式上=whatever 无论什么
但是，no matter what 只能引导状语从句,但whatev...