问题
选择题
From the teacher’s patience and understanding, I have learnt what a big responsibility______is to educate us.
A．this
B．that
C．it
D．one
答案
答案：C
本题考查it作形式主语的用法。句中have learnt后面是由what引导的感叹句, it是形式主语,动词不定式是真正的主语。