i have fallen behind in my study,so i have got to___

题目

i have fallen behind in my study,so i have got to___
A.make an effort B.make efforts C.study hard D.make effort

答案

答案是d
因为前俩个词组是有固定用法的
make an effort to do sth
make efforts to do sth.
而make effort是泛指要努力了,要争气了,
它可以单独用,后面不需要跟不定式去组句.