给出原因的简单英语句型:

　　This phenomenon exists for a number of reasons. First, … Second, … Third, …

　　这一现象的存在是有许多原因的.首先，……;第二,，……;第三，……

　　Why did …? For one thing …，for another …. Perhaps the primary reason is…

　　为什么会……?一个原因是……，令一个原因是……;或许其主要原因是……

　　I quite agree with the statement that … The reasons are chiefly as follows.

　　我十分赞同这一论述,即……，其主要原因如下: