21.The reasons for this phenomenon may be obvious . / There may be some obvious reasons for this phenomenon .
　　可能有几点很明显的原因导致该现象。

　　22.… is mainly due to the following reasons / factors .
　　……主要是由于以下原因/因素。

　　23.There are many factors deciding / influencing …
　　有许多因素决定/影响……

　　24.Effective measures should be taken as soon as possible to …
　　应该尽快采取有效的措施来……

　　25.It is an urgent thing to take effective methods to solve this problem .
　　当务之急是采取有效的方法解决这一问题。

　　26.Facing … , we should try our best to figure out the ways to change this situation .
　　而对……，我们应该努力想办法改变这种局面。

　　27.The following ways can be taken to …
　　可以采用下列方法来……

　　28.… is an effective way to …
　　……是一个……的有效的方法。

　　29.By dong … , one person can …
　　通过……，一个人可以……

　　30.In order to … , … should …
　　为了……，……应该…