on
afternoon,morning,evening与介词的搭配
1.泛指一般意义的上午、下午或晚上,通常与介词 in 连用；若是特指具体某一天的上午、下午或晚上,则与介词 on 连用.如：
The children have four classes in the morning and two in the afternoon.孩子们上午上四节课,下午上两节课.
It happened on Friday evening.这事发生在星期五晚上.
但是当 afternoon,morning,evening 等词与 early,late 连用时,即使它有定语修饰特指具体某一天的上午、下午或晚上,也通常用介词 in.如：
He arrived in the early morning of April the first.他于四月一日清晨到达.
2.在 this (yesterday,tomorrow) afternoon 这类短语中通常不用 in,on,at 这样的介词,但若语境需要,它可以与 after,by,before,until,from 等介词连用.如：
He didn’t come back until yesterday afternoon.直到昨天下午他才回来.
By tomorrow afternoon I ought to have finished the job.到明天下午的时候我应该把这工作做完了.
