It was not until dark he found he thought was the correct way to solve the problem.A. th

问题补充：

It was not until dark he found he thought was the correct way to solve the problem.

A. that; that

B. that; what

C. when; what

D. when; that

答案：

A. that; that

(答案→)B. that; what

C. when; what

D. when; that

解析：考查强调句型和宾语从句。本题第一空是强调句型，强调的是时间状语not until dark;第二空是动词find的宾语从句，what在句中做主语。句意：直到天黑他才发现了他认为是正确的解决这些问题的方法。故B正确。