Yang Li: 大家好欢迎收听BBC英语教学节目《你问我答》，我是杨莉。这是一个互动的教学栏目，你提问我们解答，通过大量例句来说明英语的使用规则和习惯用法，帮助大家提高进取。本周我选择的问题来自Lona，请我的同事Finn带读。
? I've known her since I arrived here. 自从我到了这儿就认识她了。
Yang Li: 第一句话的意思是，自从我们一起开始上学的时候我们就是朋友了。这二句话的意思是，从Maya 来伦敦学习后我就一直在帮助她。注意在since引导的从句里，动词必须是过去时：went to school; came to study in London. Let's listen again:
I have been helping Maya ever since she came to study in London.
Yang Li: Since 除了可以引导一个从句之外它后面也可以跟一个具体的时间，比如年月日等等：
We have been friends since 1995.
Jack has not seen his son since last month.
I have been waiting here since 8 o'clock.
Yang Li: 最后我想提示大家since 有两个主要的意思，除了"自从"这个意思之外，它也可以作为介词，表示，"由于，因为"。比如：
Since it's the Chinese New Year, let's go to a Chinese restaurant.
Yang Li: 因为是中国的新年咱们还是去一家中餐馆吧。
We decided to stay indoors since it was raining.
Yang Li: 由于下雨我们决定呆在家里面。这两句中的since 都是因为的意思，表示原因。
? Since it was Sunday, I stayed in bed longer. 因为(reason).
? Since he arrived, everything has been different.自从(time).
? We have been friends since 1995.自从(time).
? We decided to stay indoors since it was raining. 因为(reason).
? I've known her since I arrived here.自从(time).
? Since it's the Chinese New Year I took her to a Chinese restaurant. 因为(reason).