that he is ill is why he can't come.

问题描述:

that he is ill is why he can't come.
A That ,why B Because ,that
C /, why D Why ,that
为什么选A
是什么句型

因为这个主语从句是完整的,that是起形式上的引导作用,不可省略.
而why引导的宾语从句中,why是做原因状语的
句子的意思也很明白,就是这样.