话题作文

　　Nowadays, there are more and more X in X . It is estimated that X . Why have there been so many X ? Maybe the reasons can be listed as follows.

　　The first one is X . Besides, X The third one is X . To sum up, the main cause of it is due to X . It is high time that something were done upon it. For one thing X . For another thing, X . All these measures will certainly reduce the number of X .