It was during World War II he was in his early twenties he joined the British Army.A.

问题补充：

It was during World War II, he was in his early twenties, he joined the British Army.

A. that; when

B. when; that

C. when; when

D. that; that

答案：

A. that; when

(答案→)B. when; that

C. when; when

D. that; that

解析：本题考查定语从句及强调句。句中when引导定语从句，先行词为World War II，在从句中作时间状语，that引导强调句。句意：是在第二世界大战期间，当时他20多岁，他参加了英国军队。