on water shortage 缺水问题
no one can deny the fact that water shortage is a grave problem (严肃的问题) with which the whole world is confronted（面对）. actually, it has become so widespread that it has severely affected people’s daily life and hindered（阻碍）the development of the global economy.
a number of factors could account for the problem, but the following might be the critical（关键性的）ones. firstly，the ever-increasing （不断增长的） population is a leading cause of water shortage. as populations increase, the demand for water grows accordingly. secondly, people everywhere waste water without even realizing it(毫无意识的): showers last too long， taps are left running and so forth. last but not least, the industrial production will cause water contamination (水污染)and it will also decrease the existing water resources (现有的水资源)further more.
in view of the seriousness of the problem, effective measures must be taken before things get worse. for one thing, it is essential that laws and regulations be worked out and enforced（制定和执行） impose a heavy penalty on those who waste or contaminate waster deliberately . secondly, a large-scale education campaign should be launched to inform the public of the significance of economizing on （节约）water. with these measures taken, it is reasonable for us to believe that this problem can be perfectly solved in the near future .