问题补充:
He felt to remind the public to protect the environment.
A. his duty
B. that is his duty
C. it his duty
D. it is his duty
答案:
A. his duty
B. that is his duty
(答案→)C. it his duty
D. it is his duty
解析:此题考查it作形式宾语,真正的宾语是后面的不定式,作形式宾语的结构为 feel/ make/find等等 + it + 名词或形容词+ to do /that 从句,句意:他感到提醒公众保护环境是他的职责。所以选C。