The reasons are presented below. 原因如下。

　　There are three premier(主要的)/best/ most important, largest, significant, obvious, crucial causes as follows.

　　以下這些是造成這一問題的最主要/最好/最重要/最大/最有意義/明顯/至關重要的原因。

　　This is based on the propensity(傾向，原因) of following points.

　　這基于以下的原因。

　　The main reason is that.. 主要原因是_____________。

　　One very important argument for ..... is that....

　　_______的非常重要的原因便是____________________。

　　The reasons are quite clear. Above all, ....

　　原因非常清楚。首先(首要的是)__________。

　　The first reason can be seen by every person.

　　第一個原因其實很明顯。

　　The first and most important reason is that.....

　　第一個而且最重要的原因是______________。

　　One of the reasons that are given for....is that....

　　______________的原因之一是__________________。

　　Perhaps this is because of the simple fact that.....

　　也許，原因很簡單，亦即_____________________。

　　One of the premier causes is that(注意用詞)

　　最重要的原因之一便是______________。

　　At the risk of sounding too simplistic, it seems to me that the main propositions can be summarized in one saying.

　　這個原因可能較簡單，不過，我認為可以用一句諺語來概括，________。

　　We may look into every possible reason, however, foremost reason for .... Is ....

　　其實有很多原因，不過，造成________的最重要的原因是______________。

　　It might also be noted that....

　　需要注意的是，____________。

　　Another reason why .....(湊字數，但不可濫用) is that....(有利于寫長句)

　　What is also worth noticing is that....

　　值得一提的是___________________。

　　There is another factor that deserves some words here.

　　還有另外一個很重要的原因。

　　A more essential factor why.... Is that

　　________ 的更為重要的原因是____________。

　　A further reason why,,,, is that.....

　　________的更深層次的原因是____________。

　　In addition..此外，再者

　　Moving on to wider themes,_______

　　展開來說，_________________________。