because 是從屬連詞,接表示直接原因的從句,一般放在主句的后面,也可放在主句前面,它表示的語氣最強,在回答why的問句時,必須用because.
例如：The swimming pool won't be open today because they're making repairs.
泳池今天不開放,因為他們在修理.
Why did you move to France?
你們?yōu)槭裁窗岬椒▏?
Because my father found work in Paris.
因為我父親在巴黎找到了工作.
注意：在英語中用了because后,不可再用so.
for 是并列連詞,用來附帶解釋說明前一分句的原因或理由,for引導(dǎo)的并列句,一般放在所要說明的句子的后面.
例如：I went to see him,for I had something to tell him.
我去見他,因為我有事要告訴他.
只有therefore是表示結(jié)果的意思而不是原因.