Question

"He tried his best to solve the problem, _______difficult it was."

Answer 1

答案B
试题分析：考查让步状语从句。No
matter
+特殊疑问词引导让步状语从句，意为：无论…；意为后面接形容词difficult，所以使用how.而不是what.句意：无论问题有多难，他都全力以赴地解决它。故B正确。
考点：考查让步状语从句
点评：no
matter特殊疑问词只能引导让步状语从句；特殊疑问词ever既可引导时间状语从句也可以引导名词性从句。

Answer 2

he
tried
his
best
to
solve
the
problem,___a____difficult
it
was.
a.however
b.no
matter
c.whatever
d.although
however=no
matter
how
无论怎样....
明了吧,我是英语教师不明可问我.