第二部分：
1) it is fairly easy to find out the reason that … 找出…的原因很简单。
注： "fairly"， 再用"very"你就OUT啦!
2) some obvious reasons for … are related to the fact that … 有关…的一些显而易见的原因是和…事实有关。
3) the answer to this problem involves many interrelated reasons. for one thing, …. for another, … 这一问题的答案涉及许多相互交织在一起的原因。一个是…，另一个是…
注：interrelated reasons，相互关联的原因。
4) the causes for …, perhaps, are varied. they include…. probably the main reason is … 引起…的原因或许各种各样。它们包括…可能其主要原因是…
5) the change is chiefly caused by the fact that …其变化主要是由这样的事实引起的，即…
注："chiefly"，表示主要的。
6) the failure mainly comes from several factors that … 失败主要产生于几方面的原因，即…
注：同上，意为“主要的”。
7) among the most important reasons offered by people for …, one should be mentioned. … 在人们给出的关于…最重要的原因中，有一个值得一提。
注："offered"，这样使用，高大上有米有。
8) it is rather easy to find out the reason why …找出…为什么的原因相当容易。
注：可替代"very"。
9) the explanation for this question may involve several complicated factors, for one thing is …, for another is …对这一问题的解释可能涉及许多复杂的因素。一个是…，另一个是…
10) the change in … largely results from the fact that … 在…方面的变化很大程度上是来自这样一个事实。
注："result from"，产生于…， 由…引起。
11) there are several causes of this significant growth in … 在…方面的显著增长是许多原因造成的。
12) 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。
13) beyond these obvious reasons, however, lies a deeper cause: 然而在这些明显的原因之下隐藏着一个更深层的原因。
14) one of the reasons that is given for … is that … 已给出的关于…的原因之一是…
15) although … is probably the most important determinant, it is not the only explanation for … 虽然…可能是最重要的决定因素，但并不是对…的唯一解释。
16) perhaps this is because of the simple fact that … 这可能是因为一个简单的事实…
17) the factors for … are complex. 有关…的因素十分复杂。