Question

__the morning they usually do sports. But___ yesterday morning they cleaned their
A. In, on        B. In, /        C. On, on

Answer 1

A

试题分析：泛指在早上，英语为in the morning，具体到某一天要用介词on。句意：通常他们早上运动。但是在昨天他们打扫了房间。故选A。