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? …的變化/增加/下降/增長有幾個方面的原因/因素。首先……，其次……?
　　例：人們道德觀的劇烈變化可能有不同的原因。?

　　7? 某事的原因/起因很復雜/不一/深刻。有些人歸因于……，有些人歸結為……，還有些人認為是……的結果。?
　　例：流行住在一起的原因既不同又復雜。?

　　8? 某事物的成功/失敗/改變/增長/下降主要/大體上是由于以下的因素。一個是……，另一個是……，還有一個是……
　　例：中國經濟的崛起主要是由于以下的因素。?

　　9? 為什么……？首先……；其次……；也許最根本的/最大的原因是……?
　　例：為什么社會越來越趨于追求權力？
?
　　10?要提供/辨別/找到某事物的每一個原因并不簡單，但總體上有三個/一些相對較為突出的因素。?
　　例：要找到青少年離家出走人數增長的每一個原因并不容易，但總體上有兩個因素較為突出。?