初中英语十大时态的定义,用法,结构及例句答:三、现在完成时用法1、现在完成时可以用来表示发生在过去某一时刻的、持续到现在的情况,常与for, since连用。 e.g. Mary has been ill for three days. I have lived here since 1998.2、现在完成时往往同表示不确定的过去时间状语连用, 如already, yet, just, before, recently, lately等:e.g. He has ...
在英语中,介词是什么?答:(1)简单介词:about, across, after, against, among, around, at, before, behind, below, beside, but, by, down, during, for, from, in, of, on, over, near, round, since, to, under, up, with等等。(2)合成介词:inside, into, outside, throughout, upon, without, within(3)短语介词:...