difficult it is he is determined to the experiment.A. No matter how; have a go atB. Ho

问题补充：

difficult it is, he is determined to the experiment.

A. No matter how; have a go at

B. However; have a go for

C. Whatever ; have a go

D. No matter what; have a go at

答案：

(答案→)A. No matter how; have a go at

B. However; have a go for

C. Whatever ; have a go

D. No matter what; have a go at

解析：考查让步状语从句和固定短语。句意“无论有多么困难，他都决心尝试做那个实验。”修饰形容词应该用how，排除C、D；have a go at“尝试”。故选A。