Question

(2005·天津)

He tried his best to solve the problcm, ________ difficult it was.

[　　]

A．however

B．no matter

C．whatever

D．although

Answer 1

答案：A
解析：

从结构上看，填上一个词应使逗号后的分句成为一个状语从句。A、C、D三项均可引导一个状语从句。从意思上看应选however。