原因狀語從句主要的有because, as, since, seeing (that), now (that), considering (that) 等。如：
1. 由because引導He couldn’t get to school because he had a cold. 他因患感冒而未能去上學。I can’t take the examination because I am ill. 我不能參加考試因為我生病了。He distrusted me because I was new. 他不信任我是因為我是新來的`。Because I worked fast, I finished early. 因為我幹得快，所以我完成得早。They can’t have gone out because the light’s on. 他們不可能出去了，因為燈還亮著。He could not concentrate because the room was noisy. 他不能集中思想，因為房裡太吵。I read no further than the caption because the subject of the article seemed uninteresting. 我只看了標題，因為文章題目似乎不引人興趣。I could have gone with you because I was there at that time. 我本來可以和你一道去的，因為那時我也在那裡。
2. 由as引導As all the seats full I stood up. 因為所有座位都有人，我就站了起來。As it’s raining, we’ll have to stay at home. 因為天下雨，我們得待在家裡。As all the seats were full he stood up. 由於所有座位都有人了，他站了起來。We didn’t know what to do as we are not his parents. 我們不知怎麼辦好，因為我們不是他的父母。
3. 由since引導Since everybody is here, let’s begin our discussion. 大家都到了，我們就開始吧。Since we’ve no money, we can’t buy it. 因為我們沒有錢，我們沒法買它。He could not answer the question, since he had not made up his mind. 他不能回答這個問題，因為他還沒拿定注意。
4. 由4. seeing that引導Seeing that it is 8 o’clock, we’ll wait no longer. 由於時間已到8點，我們將不再等了。Seeing that it’s raining，we’d better stay indoors. 既然外邊在下雨，我們最好待在室內。既然外邊在下雨，我們最好待在室內。Now that you are here, you’d better stay. 你既然來了，最好還是留下吧(既來之，則安之)。5. 由now that引導Now that you are here, you’d better stay. 你既然來了，最好還是留下吧。Now that you’re well again. you can travel. 既然你身體好了，你現在可以旅行了。Now that you mention it, I do remember the incident. 經你一提，我想起那事了。注：其中的 that 通常可以省略。如：Now (that) John’s arrived, we can begin. 既然約翰到了, 我 們可以開始了。
