3. as 引导原因状语从句时表示附带说明的“双方已知的原因”，语气比since弱，较为正式，位置较为灵活(常放于主句之前)。例如：As it is raining, you’d better take a taxi. 既然在下雨，你最好乘出租汽车。// As you are tired, you had better rest. 既然累了，你最好休息一下。// I went to bed early, as I was exhausted. 我睡得早，因为我筋疲力尽了。
【学苑教育学习网】http://www.xycentre.org/
【辅导报班电话】：400－621－8199
关注学苑管理类联考微信号：xyuan62513012
