4. 商業捕魚 　　A Brief History of World Commercial Fishing 　　[2.圖表描述段] As is shown in the pictures ,with the increase of commercial fishing ,the number of fishes dramatically decreased .In one pictures ,there were various kinds of fish and only one fishing-boat in 1900 .On the contrary ,in1995 there was only one fish ,with many fishing-boats. 　　[5.意義闡述段] The purpose of this picture is to show us that due attention has to be paid to the decrease of ocean resources .Owing to over-fishing the number of fishes has obviously dropped .If we let this situation go as it is ,we do not know where fish will be in the future .By that time ,our environment will suffer a great destruction . 　　[10.建議措施段] Therefore ,it is imperative for us to take drastic measures .For one thing ,we should appeal to our authorities to make strict laws to control commercial fishing .For another ,we should enhance the awareness of people that the ocean resources are very vital to us .Only in this way can we protect our ocean resources .Also I believe that we humans can overcome this difficulty ,and we will have a brighter future .