2017届高考英语一轮复习知识梳理练习：必修1 Unit 2 Heroes（北师大版）_高考复习指南

2017届高考英语一轮复习知识梳理练习：必修1 Unit 2 Heroes（北师大版）

　　Unit 2 Heroes

　　(60分钟81分)

　　Part A

　　一、阅读理解(共8小题;每小题2分,满分16分)

　　Death is natural,but do you have any idea of the process of dying?Modern scientists divide the process of dying into two stages—clinical or temporary death and biological death.Clinical death occurs when the vital organs,such as the heart or lungs,have ceased to function,but have not suffered permanent damage.The organism can still be revived(复活).Biological death occurs when changes in the organism lead to the “breaking up” of vital cells and tissues.Death is then unchangeable and final.

　　Scientists have been seeking a way to lengthen the period of clinical death so that the organism can remain alive before biological death occurs.The best method developed so far involves cooling of the organism,combined with narcotic(麻醉的) sleep.By slowing down the body’s metabolism(新陈代谢),cooling delays the processes leading to biological death.

　　To illustrate how this works,scientists performed an experiment on a six-year-old female monkey called Keta.The scientists put Keta to sleep with a narcotic.Then they surrounded her body with ice-bags and began checking her body temperature.When it had dropped to 28 degrees the scientists began draining(使流光) blood from an artery(动脉).The monkey’s blood pressure decreased and an hour later both the heart and breathing stopped:clinical death set in.For twenty minutes Keta remained in this state.Her temperature dropped to 22 degrees.At this point the scientists pumped blood into an artery in the direction of the heart and started artificial breathing.After two minutes Keta’s heart became active once more.After fifteen minutes,spontaneous(自发的)breathing began,and after four hours Keta opened her eyes and lifted her head.After six hours,when the scientists tried to give her a penicillin injection,Keta seized the syringe(注射器)and ran with it around the room.Her behavior differed little from that of a healthy animal.