I didn’t go because I was afraid. 我沒有去是因為怕。/ 我不是因為怕才去的。
不過若because之前有just修飾，一般認為not 是否定從句的：
You shouldn’t get angry just because some people speak ill of you. 你不要因為有人說你壞話而生氣。
三、because不能與so連用
漢語習慣上說“因為…所以…”，但英語習慣上卻不能將 so與because 連用：
因為下雨，所以我們得呆在家裡。 正：Because it was raining, we stayed at home. / It was raining, so we stayed at home. 誤：Because it was raining, so we stayed at home.
四、because從句與 because of短語的轉換
Because引導的原因狀語從句有時可與because of 短語轉換，because of後加的原因可以為好或壞
但最正規的還是because
He can’t come because he is ill. / He can’t come because of his illness. 他因病不能來。
比較：because, since,as和for的區別：
1) because引導的原因狀語從句一般放於主句的後面，because從句位於句首時要用逗號分開，放在句末時，可不用逗號分開。because表示直接原因， 語氣最強， 最適合回答why引導的疑問句。because of 也表示原因，但它後面不接從句, 只能接名詞, 代詞或動名詞。注意：because 和so 不可同時出現在一個句子裡。
I do it because I like it. = I like it so I do it.We went by bus because it was cheaper. = It was cheaper so we went by bus.He can’t go to school because of his illness.
2) since引導的原因狀語從句一般放於主句之前表示已知的、 顯然的理由(通常被翻譯成“既然”= now that )， 較為正式， 語氣比because弱。
Since you are free today, you had better help me with my mathematics.Since you don"t trust him, you should not employ him.Now (that) you are grown up, you should not rely on your parents.
3) as 引導原因狀語從句時表示附帶說明的“雙方已知的原因”，含有對比說明的意味，語氣比since弱， 較為正式， 位置較為靈活(常放於主句之前)。
As it is raining, you’d better take a taxi.As you are tired, you had better rest.I went to bed early, as I was exhausted.
原因狀語從句
拓展資料:
原因狀語從句指在句中用來說明主句原因的從句。引導原因狀語從句的從屬連詞有because（因為）, as（由於）, since（既然）, now(that)（既然）, when（既然）, seeing (that) （由於，鑑於）, considering (that)（考慮到）, for（為）, given (that) （考慮到）等。
一、引導原因狀語從句的從屬連詞
主要的有because,for,in that,for the reason that;as,seeing (that), seeing as;since;now (that); considering (that)等：
The woolly shrank because it was washed badly. 毛衣因為洗滌的方法不好而縮水
【注】除以上提到的大家比較熟悉的引導原因狀語從句的從屬連詞外，when有時也可引導原因狀語從句(when表示“既然”)
I won’t tell you when you won’t listen. 既然你不想聽，那我就不告訴你了。
二、關於not…because結構
該結構中的否定詞有時否定主句，有時否定從句，一般要根據句子的意思作出正確或合乎邏輯的理解。若not否定主句，最好在because之前用逗號，否則會引起歧義，如下句在沒有特定上下文時就有兩種解釋：
I didn’t go because I was afraid. 我沒有去是因為怕。/ 我不是因為怕才去的。
不過若because之前有just修飾，一般認為not 是否定從句的：
You shouldn’t get angry just because some people speak ill of you. 你不要因為有人說你壞話而生氣。
三、because不能與so連用
漢語習慣上說“因為…所以…”，但英語習慣上卻不能將 so與because 連用：
因為下雨，所以我們得呆在家裡。 正：Because it was raining, we stayed at home. / It was raining, so we stayed at home. 誤：Because it was raining, so we stayed at home.
四、because從句與 because of短語的轉換
Because引導的原因狀語從句有時可與because of 短語轉換，because of後加的原因可以為好或壞
但最正規的還是because
He can’t come because he is ill. / He can’t come because of his illness. 他因病不能來。
比較：because, since,as和for的區別：
1) because引導的原因狀語從句一般放於主句的後面，because從句位於句首時要用逗號分開，放在句末時，可不用逗號分開。because表示直接原因， 語氣最強， 最適合回答why引導的疑問句。because of 也表示原因，但它後面不接從句, 只能接名詞, 代詞或動名詞。注意：because 和so 不可同時出現在一個句子裡。
I do it because I like it. = I like it so I do it.We went by bus because it was cheaper. = It was cheaper so we went by bus.He can’t go to school because of his illness.2) since引導的原因狀語從句一般放於主句之前表示已知的、 顯然的理由(通常被翻譯成“既然”= now that )， 較為正式， 語氣比because弱。
Since you are free today, you had better help me with my mathematics.Since you don"t trust him, you should not employ him.Now (that) you are grown up, you should not rely on your parents.3) as 引導原因狀語從句時表示附帶說明的“雙方已知的原因”，含有對比說明的意味，語氣比since弱， 較為正式， 位置較為靈活(常放於主句之前)。
As it is raining, you’d better take a taxi.As you are tired, you had better rest.I went to bed early, as I was exhausted.4) for引導的是並列句表示原因但並不說明主句行為發生的直接原因， 只提供一些輔助性的補充說明， for引導的並列句只能放於主句之後並且必須用逗號將其與主句隔開。
He could not have seen me, for I was not there.He seldom goes out now, for he is very.