每天英语知识点，普及英语小知识。
hello，大家好，我是知识君。
上期练习题答案为：B C A
今天要和大家分享的是英语中“since”作为连词的用法！
课前小测试
_____ the students came from different countries, they got along (相处) quite well in the summer camp.
A While
B Unless
C Since
D Until
（答案在文末）
知识点解读
since作连词时，有两个意思需要记忆。一起看两个例句吧：
1 Since we were 5, we have been friends.
2 Since they're very hard to find, these stones are rather expensive.
两句话中，since表达了两层含义：
1【表时间】自从（某时起，就一直。。。）
注意：从句一般用过去时态，主句用完成时态（如have done/had been doing)
例如：
She had been talking to her mother about the lives of homeless people since they first saw the homeless man.（2017高考 北京卷 完形）
自从他们第一次看到那流浪汉，她就一直跟她妈妈聊流浪人群的生活现状。
2【表原因】由于、既然（同as）
那么之前两个例句的意思，就很清楚啦：
1 Since we were 5, we have been friends.
从5岁开始，我们就一直是朋友。
2 Since they're very hard to find, these stones are rather expensive.
由于这些石头非常稀有，所以它们的售价较为昂贵。
======敲黑板Sum Up======
阅读中，一旦确认since作连词，
1 首先想"由于、既然"、"自从"这两个意思哦
2 表"自从"时，观察主句时态→完成时态
好了，since做连词的用法大家都记住了吗？下面我们一起来练习一下吧！
练习题
Since everything can be done from home with computers, there’s no need to dress up for work anymore.
since在这句话中的意思是 _____
A 由于、既然
B 自从
He has been back to the office a few times _____ he retired.
A if
B since
C as
D because
_____ scientists have learned a lot about the universe, there is much we still don't know.
A Once
B Since
C Though
D If
答案放送
课前小测试答案：A（此处while意思为“虽然，尽管”）
练习题答案：下期文章公布哦！
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