Jim didn’t realize his little sister was crying what he had said.
A. because
B. because of
C. as
D. since
网友回答
A. because
(答案→)B. because of
C. as
D. since
解析：考查连词和介词用法。ACD三项表示原因的时候，以后要接完整的句子做原因状语从句。只有because of后面要接名词或者名词性的短语做宾语，形成介词短语在句中做状语。本题的what he had said=his words是指他所说的话。故B正确。