Question

---she couldn't understand was ----fewer and fewer students showed interest in her lessons

A what why

B that what
C what because
D why that

Answer 1

---she couldn't understand was -A---fewer and fewer students showed interest in her lessons
A what why

B that what
C what because
D why that
答案解析逗慧：答案A ：

【What】she couldn't understand was 【why】fewer and fewer students showed interest in her lessons

前面是连接代词what引导的主语从句， 后面由连接知渣副词why 引导表语从句

中搭指悄文：她无法理解的是为什么越来越少学生表现得对她上课不感兴趣

Answer 2

A What Why
（What） she couldn't understand was （why） fewer and fewer students showed interest in her lessons.
他不能明白的是为啥越来越少学生对她的课堂感兴趣。

希握缓坦望的你段桐有哪亏帮助！