对于此，我有如下两点愚见：
The reasons are chiefly as follows. 主要原因如下：
There are numerous reasons why ____, and I would like to explore a few of the most important ones here.
为什么___________，原因很多，在此列举几个较为重要的原因
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.
以下这些是造成这一问题的最主要/最好/最重要/最大/最有意义/明显/至关重要的原因。
This is based on the propensity(倾向，原因) of following points.
这基于以下的原因。
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.
第一个原因其实很明显。