Which of the following is an idi

Which of the following is an idiom verbal in nature?（ ）
A、cut and dried
B、fly in the ointment
C、call it a day
D、in clover
【正确答案】：C
【题目解析】：cut and dried(（枯燥无味的）是形容词性习语；fly in the ointment（美中不足）是名词性习语；in clover（养尊处优）是副词性习语。call it a day（收工）是动词性习语。所以选C。