difficult it might be I will try my best to work it out.A. WhateverB. HowC. HoweverD. W

问题补充：

difficult it might be, I will try my best to work it out.

A. Whatever

B. How

C. However

D. What

答案：

A. Whatever

B. How

(答案→)C. However

D. What

解析：考查however引导的让步状语从句：句意： --无论这有多难，我都会尽力把它做好的。however引导的让步状语从句结构是However+adj/adv+主谓，选C。