原因狀語從句的從屬連詞because、as和for的選擇，是大家經(jīng)常會(huì)碰到的問題，尤其在做完形填空類的題目時(shí)，究竟該選擇哪個(gè)，經(jīng)常會(huì)困擾大家。不用擔(dān)心，貼心的小編為大家整理了相當(dāng)詳細(xì)的解析：

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在because，since，as這三個(gè)從屬連詞中，以because語勢最強(qiáng)，since次之，as又次之。Because通常表示“新信息”，即表示一種未知的原因，而since / as則表示已知原因。所以，如前所述，在回答why-問句時(shí)要用because-分句，而不用for-分句，同樣也不用since- / as-分句。作為分裂句中心成分，如前所述，也只能用because-分句之前可用否定詞或其他修飾語，這種分句之前還可以用某些并列連詞，但for-分句不可以，同樣的since- / as-分句也不可以。關(guān)于這一點(diǎn)，我們再補(bǔ)充例子：

I went to the state university chiefly because the tuition was cheaper.

She didn’t want to go to Africa, probably because the weather is too hot.

I’m going there tomorrow because I have to, not because I want to.

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由于since- / as-分句通常表示已知的原因，所以常常出現(xiàn)于句首，這又是它們與for-分句用法上不同之處。

例如：

As China is a long, narrow country, the temperature varies considerably from north to south.

Since he had a certain talent for composition, his English master encouraged him to write little pieces for the college magazine.

當(dāng)然since- / as-分句也可位于句尾，作為一種補(bǔ)充說明。

例如：

I’ll have you ask someone else, since you can’t answer this question.

He saw her, as they were both getting off the bus at the same time.

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看完了小編整理的語法解析，大家對打敗because、as和for這三個(gè)“小怪物”是不是多了幾分信心呢？趕快收藏起來吧~