Never believe all you hear, never regret what you have never lost, and never throw away what you have in your hands.
A. that
B. which
C. what
D. when
网友回答
(答案→)A. that
B. which
C. what
D. when
解析：考查定语从句的关系词。先行词是all，定语从句缺少hear的宾语，所以用that引导，which不能引导先行词是all的定语从句。选A。