Nowadays ,there are more and more ______A（代表一种现象）in some big cities . It is estimated that______(用具体数据说明该现象) Why have there been so many A ?

　　Maybe the reasons can be listed as follows. The first one is that_____(原因一) .Besides, _____________(原因二) . The third reason is _________( 原因三).To sum up ,the main cause of A is due to _______( 指出主要原因) .

　　It is high time that something were done upon it. For one thing,________ (解决建议一).On the other hand ,_______(解决建议二). All these measures will certainly reduce the number of A.