（ ）his had suddenly changed his idea made（ ） necessary for me to change my plan
问题描述：
（ ）his had suddenly changed his idea made（ ） necessary for me to change my plan
（ ）his had suddenly changed his idea made（ ） necessary for me to change my plan.
A./;that B;whether;it's C.that;it D.what；this
为什么呢?
答
前面是个主语从句,用that引导,“他突然改变主意”这件事
后面说,这件事使我必须改变主意,it 指后面的不定式for me to change my plan