A warm thought suddenly came to me I might substitute the hero to buy some flowers for hi

问题补充：

A warm thought suddenly came to me I might substitute the hero to buy some flowers for his mother’s 60th birthday.

A. if

B. when

C. that

D. which

答案：

A. if

B. when

(答案→)C. that

D. which

解析：考查同位语从句。thought“想法，念头”；came to sb.“（想法）出现在某人头脑中”；that引导同位语从句，是对thought的补充说明。故选C。