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: