原因狀語從句
    連接詞：because，since，as，for，now that，in that，owing to，due to，thanks to，because of，as a result of;
    比較：because，since，as和for
    1)because語勢，用來說明人所不知的原因，回答why提出的問題。當原因是顯而易見的或已為人們所知，就用as或 since。
    I didn't go, because I was afraid.
    Since /As the weather is so bad, we have to delay our journey.
    2)由because引導的從句如果放在句末，且前面有逗號，則可以用for來代替。但如果不是說明直接原因，而是多種情況加以推斷，就只能用for。
    He is absent today, because / for he is ill.
    He must be ill, for he is absent today.
    now that ：既然;
    in that :因為，通常只能放在句中，強調(diào)重要的，的的原因;
    eg：Now that this semester is finished, I am going to rest a few days and take a trip.
    Human beings are different from animals in that human can speak and think.
    owing to, due to, thanks to, because of , as a result of等短語后面只能接詞或短語，不能接從句。