原因状语从句.

2.----- Why can't you go there now? because -----_____ I’m too busy.
3.(True or false) Becuse I had nothing better to do, so I decided to go to Wufeng Mountain with them.
8.Mr Brown returned home just ___ his family were having supper. A then B as C when D while 9. _______he took part in the competition, he won a second prize. A The first time B For the first time C At the first time
C. not until midnight that he went D. until midnight when he did not go
4. Unlike watching TV, reading is a highly active progress (过程) ,___ it requires attention as well as memory and imagination. A. until B. but C. unless D. for 5.She thought I was talking about her daughter, ___ ,in fact, I was talking about my daughter. A. whom B. where C. which D. while
ห้องสมุดไป่ตู้
I stayed at home because it rained. —Why is she absent? —Because she is sick. 在强调句型中，只能用because It was because I missed the early bus that I was late for school.
because 1. 语气强，可放在主句前或后，表示 直接因果关系，回答why 提出的疑问 句，用在强调句式结构中。汉语中的： “因为-----所以------”在英语中的表 达只能使用because 或so 中的一个， 不能同时使用这两个单词。 1. 那个男孩因病缺席。 The boy was absent because he was ill. It was because he was ill that the boy was absent.
6.____ quite recently, most mothers in Britain did not take paid work outside the home. A.Before B. Until C. From D. Since 7.____ you are leaving tomorrow, we can eat dinner together tonight. A.For B. Since C. Before D. While
要点：不要把连接词 because与介 词短语because of ( + 名词或-ing形 式) 相混淆；
for表明附加或推断的理由,它所引导的 分句只能放在句子后部 ,并且前后两个 分句间的逻辑关系不一定是因果关系, 其间用逗号隔开. The days are short, for it is now December. It must have rained, for the ground is wet.
要点：不要把连接词 because与介词 短语because of ( + 名词或-ing形式) 相混淆； He lay in bed because he had caught a bad cold.
He lay in bed because of a bad cold.
since表示显然的或已为人所知的理由， 常译为“因为”、“既然”，通常置于句 表示一种含有勉强语气的原因。
now that 既然 . 常放句首. Now that you have left university, you will have to find a job. Now that everybody is here, let's begin the discussion.
1.Don’t be afraid of asking for help ____ it is needed. A.unless B.since C.although D.when
because, since, as, for,这几个词都是 表示“原因”的连词，语气由强至弱 依次为：because＞since＞as＞for 其中because, since, as均为从属连词， 引导原因状语从句；而for 是并列连词， 引导并列句。
1. because表示直接原因，其语气最强。 常用来回答why的提问
2.Mary was making a dress ___ she cut her finger. A. when B. while C. as D. after
3.It was _____ back home after experiment . A. not until midnight did he go B. until midnight that he did not go
Since he asks you, you'll tell him why. Since everyone is here, let's start.
as含义与since相同，但语气更弱， 没有since正式 We all like her as she is kind. As I had a cold, I was absent from school.