6) There are several reasons/causes/factors for the changes/increase/decline/growth in...(First,...Second...)
　　(e.g. There are probably a variety of reasons for the drastic changes in people"s moral concepts.)

　　7) The reasons/causes/factors for sth. are complex/varied/profound. (Some attribute it...Others put it down to...Still others owe it to...)
　　(e.g. The causes for the prevalence of living together are varied and complex.)

　　8) The success/failure/change/increase/decline(in sth.) mainly/largely stems/derives/results from the factors as follows.(One lies in...Another is found in...Still another consists in...)
　　(e.g. The rise in China"s economy mainly derives from a number of factors/the factors as follows.)

　　9) Why has/did/is...? (For one thing/...For another...Perhaps the most fundamental/adequate/competent reason is...)
　　(e.g. Why is there a growing drift toward power-seeking in society?)

　　10) It is no easy/simple task/job to furnish/identify/find every reason / cause for sth., but/while, on the whole, three/some factors shout louder/weigh heavier than others/stand out from others.
　　(e.g. It is no easy job to find every reason for the increase in the number of teenagers who run away from their homes, but, on the whole, two factors shout louder than others.)

　　6? …的变化/增加/下降/增长有几个方面的原因/因素。首先……，其次……?
　　例：人们道德观的剧烈变化可能有不同的原因。?

　　7? 某事的原因/起因很复杂/不一/深刻。有些人归因于……，有些人归结为……，还有些人认为是……的结果。?
　　例：流行住在一起的原因既不同又复杂。?

　　8? 某事物的成功/失败/改变/增长/下降主要/大体上是由于以下的因素。一个是……，另一个是……，还有一个是……
　　例：中国经济的崛起主要是由于以下的因素。?

　　9? 为什么……？首先……；其次……；也许最根本的/最大的原因是……?
　　例：为什么社会越来越趋于追求权力？
?
　　10?要提供/辨别/找到某事物的每一个原因并不简单，但总体上有三个/一些相对较为突出的因素。?
　　例：要找到青少年离家出走人数增长的每一个原因并不容易，但总体上有两个因素较为突出。?