13.B,occasion 14.B,process 15.A,against
16.A,order; 17.D,conteibutes; 18.A,Instead
19.C,volume; 20A，award; 21A，advantage
22A，revived; 23D; efficient; 24C;negotiate
25D to be repaired ; 26A; had never been
27C; where; 28C;have; 29B; when
30B;would have; 31D，has; 32C.which
33，D; 34，A; 35，C ;
36，D depressing; 37，D a
开头 the first way
38，B out of; 39，B barrier; 40，C see
41，A scoot; 42，B he got
开头 the latest
43.C a student who; 44.A catch
45.C the title; 46.B An 。。ending
48C;for thirteen 49A;Rain; 50C;relaxing; 51D;the area; 52A 40
T1：B 我们一定 T2C 俗话说 T3：D “伸手”既可能指
T4：A 已有 T5：A 尽管已四十好几
In the past hundred years, there have been frequent natural disasters, such as floods, droughts, mud-rock flows, seismic sea waves, earthquakes, windstorms and the stretching of new deserts. The disasters have killed millions upon millions of people, destroyed countless homes, and wiped out numerous pieces of fertile land.
Now more and more people become aware that those disasters have much to do with what we have done to the earth. We have cut down too many trees in the forests, we have badly polluted the environment, and we have shocked our own home-planet time and again with tremendously powerful explosions of nuclear bombs.
As a result, climates have become abnormal, rainwater rushes down hillsides angrily, and the underground energy goes up to revenge itself on us.
The earth is our only home-planet. It is urgent for us to stop damaging it, and to do our best to protect it and make it a lovely place suitable to live in, for we have nowhere to go and survive except where we are now.