表原因的时候 because for since 有什么区别 Mother does not allow him to play computer games ,but she is afraid that it will be bad for his syudies.答案是把but 改成because .请问可以改为for 或since 如果不行,为什么?也即

表原因的时候 because for since 有什么区别 Mother does not allow him to play computer games ,but she is afraid that it will be bad for his syudies.答案是把but 改成because .请问可以改为for 或since 如果不行,为什么?也即
表原因的时候 because for since 有什么区别
Mother does not allow him to play computer games ,but she is afraid that it will be bad for his syudies.答案是把but 改成because .请问可以改为for 或since 如果不行,为什么?
也即是问都引导从句,表原因的时候 because for since 有什么区别?

表原因的时候 because for since 有什么区别 Mother does not allow him to play computer games ,but she is afraid that it will be bad for his syudies.答案是把but 改成because .请问可以改为for 或since 如果不行,为什么?也即
看下面解释你就明白了
because
because引导原因状语从句语气最强,表示直接原因,常用来回答由why提出的问题,所引导从句可放在主句前,也可放在主句后.例如：
"Why did you do it?" "Because Carlos told me to".
We can't go to Julia's party because we're going away that weekend.
Because he didn't catch the last bus,he had to walk home.
Why are you late for school Because I missed the first bus.
since
since “因为,既然” 侧重主句,主句表示显然的或已知的理由.强调说话者和听者双方都知道的原因,常译为“既然”,一般用在这样的句子里.例如：
Since we've got a few minutes to wait for the train,let's have a cup of coffee.
Since you are not feeling well,you may stay at home.
Since everybody is here,let's begin the meeting.
Since I am a boy,let me carry the case.
Since/As you are busy,you had better not go with us.
Since we have no money,we can't buy that vase.
for
for “因为,由于”表明附加或推断的理由,引导的分句前常有逗号.for分句不放句首.是用来附带解释或说明前一分句的原因和理由.例如：
Day breaks,for the cock crows.
It must have rained last night,for the ground is wet.
I won't go in,for my father is there.
He must be ill,for he is absent.
I went to see him,for I had something to tell him.

for可以吧
for表示原因是的时候不能放在句首
since是有既然的意思 但多为比较牵强的原因
比如：since everyone's here,let's begin our meeting
但是不是每个人在这里我们也是要开会的 这个意思。
because比较万能 随便你怎么用 都没有错的

看了以上，我在补充和总结一下：
because\since\as都可以表是原因，是从属连词，引导原因状语从句。
for也可表原因，是等立连词，连接并列分句。for不可以放句首。
because是正式用语，用于句中（不用于句首），常用于回答why的提问。
since是表经过思考分析的原因“既然”可放于句首和句中，都可以。
as是显而易见的原因“由于”，可放于句...

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看了以上，我在补充和总结一下：
because\since\as都可以表是原因，是从属连词，引导原因状语从句。
for也可表原因，是等立连词，连接并列分句。for不可以放句首。
because是正式用语，用于句中（不用于句首），常用于回答why的提问。
since是表经过思考分析的原因“既然”可放于句首和句中，都可以。
as是显而易见的原因“由于”，可放于句首和句中。

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