精选优质文档-倾情为你奉上8B Unit21.Ive been there be fore. 我以前去过那里。before副词“以前”。常与现在完成时连用，也可与一般过去时连用。He has never seen such a huge stone before.他以前从未见过这么大的石头。before介词或连词“在之前”，可表示时间、位置、顺序等。My father usually goes to bed before 9:00 p.m.我父亲通常在晚上9点之前睡觉。（介词）Turn off the light before you leave the room.离开房间前关上灯。（连词）3.Can I join you?我可以和你一起去吗?join及物动词“加入”，表示加入某一组织、党派、社会团体或某一人群中，从而成为其成员。join后常出现club，army，team，group以及表示人称代词宾格的单词等。My father joined the army after he finished middle
