1.There are several reasons for…, but in general, they come down to three major ones.有几个原因……，但一般，他们可以归结为三个主要的。

　　2.There are many factors that may account for…, but the following are the most typical ones.有许多因素可能占...，但以下是最典型的。

　　3.Many ways can contribute to solving this problem, but the following ones may be most effective.有很多方法可以解决这个问题，但下面的可能是最有效的。

　　4.Generally, the advantages can be listed as follows.一般来说，这些优势可以列举如下。