摘要:So far, several cases of a disease, as H1N1, are reported to have been found in the country. A. knowing B. to be known C. having known D. known

网址:http://m.1010jiajiao.com/timu3_id_3226616[举报]

I give two examples as to why intelligent life may not actually exist, though I admit that for me, or even for a physicist who devoted his or her entire life to researching and studying the universe, it's shocking to claim that completely no life exists elsewhere.

Keeping that in mind, I'd just like to consider conditions elsewhere in the known universe. You really only need to look at our own solar system or the Earth at certain periods in its own history to appreciate that most places are much worse and much less suitable for life than our mild, watery globe.

So far, space scientists have discovered about seventy planets outside the solar. But it appears that if you wish to have a planet suitable for life, you just have to be very lucky, and the more advanced the life is, the luckier you'll have to be. I'm by no means a space observer, but I can recognize some particularly fortunate breaks we've had on the Earth. For example:

We are, to a degree, at the right distance from the perfect type of star, the one that is big enough to radiate a huge amount of energy, but not so big as to bum itself out quickly. Had our sun been ten times as huge, it would have burnt out completely after only ten million years, instead of ten billion and surely we would not exist. Too near, everything on the Earth would have boiled and withered away; any further, everything would have frozen over.

The universe is a surprising place, and our existence within it is a wonder. If a long and unimaginably complex sequence of events dating back 4.6 billion years or so hadn't happened in a particular manner at a particular time --if, to take just one example, the dinosaurs hadn't been wiped out by a meteor(流星)--we might still be a few centimeters long, with whisker(胡须) and a tail, and you'll be reading this in a cave somewhere.

1.What's the best title for this passage?

A. No Life Exists out of the Earth

B. Seventy Planets Discovered

C. A Place Full of Wonders

D. Perfect Conditions for Life

2.What makes the Earth more suitable for life than other planets in the solar system?

A. The Earth is the only planet that can receive energy from the sun.

B. The sun is at the right distance from us and in proper size.

C. The distance between the planets was neither too long nor too near.

D. The dinosaurs were no longer a threat to the Earth.

3.What does the underlined phrase "withered away" in the 4th paragraph mean?

A. Exploded.    B. Expanded.  C. Floated away.       D. Dried and died.

4.Where does the text probably come from?

A. A history book.     B. A magazine.  C. A science fiction.          D. A famous novel.

 

查看习题详情和答案>>

All too often, a choice that seems sustainable(可持续的)turns out on closer examination to be problematic. Probably the best example is the rush to produce ethanol(乙醇) for fuel from corn. Corn is a renewable resource —you can harvest it and grow more, almost limitlessly. So replacing gas with corn ethanol seems like a great idea. 

   One might get a bit more energy out of the ethanol than that used to make it, which could still make ethanol more sustainable than gas generally, but that’s not the end of the problem. Using corn to make ethanol means less corn is left to feed animals and people, which drives up the cost of food. That result leads to turning the fallow land –including, in some cases, rain forest in places such as Brazil—into farmland, which in turn gives off lots of carbon dioxide (CO) into the air. Finally, over many years, the energy benefit from burning ethanol would make up for the forest loss. But by then, climate change would have progressed so far that it might not help.

   You cannot really declare any practice “sustainable” until you have done a complete life-cycle analysis of its environmental(环境的) costs. Even then, technology and public keep developing, and that development can lead to unforeseen and undesired results. The admirable goal of living sustainably requires plenty of thought on an ongoing basis.

1.What might directly cause the loss of the forest according to the text?

A. The growing demand for energy to make ethanol

B. The increasing carbon dioxide in the air

C. The greater need for farmland

D. The big change in weather.

2.The underlined word “it” in the second paragraph refers to “           ” 

A. the energy benefit                                              B. the forest loss 

C. climate change                                           D. burning ethanol 

3.The author thinks that replacing gas with corn ethanol is           . 

A. impractical                    B. acceptable               C. admirable         D. useless 

4.What does the author mainly discuss in the text? 

A. Technology                          B. Sustainability

C. Ethanol energy            D. Environmental protection 

 

查看习题详情和答案>>

I can still remember the first day when I met my best friend. I hid behind my mother and she hid behind her grandmother,   36  to look at each other. But we soon lost the   37   and started playing with each other. In the 7th grade, I first lost touch with her. She was going through family problems and I deserted her to be with the “cooler people”.   38  of my new friends liked her as much as I did because they knew she had “problems”. However, every summer we would   39  sit at each other’s home and watch soap operas and talk about everything we liked.

It was last year when I noticed the problem. I guess I was just too busy in high school to realize she needed someone there for her. Well, she made a new “best friend” and   40  did I. Then I didn’t know why, but she started cutting herself.

She was diagnosed with clinical depression(抑郁症). I was very   41_  at first, but with the late night calls, we still stayed in touch. I wanted to be there for her since her new best friend   42  deserted her. When people were calling her   43 , I knew I still   44  her like a sister.

Yesterday she came   45  me and said this,” I never knew what a best friend was   46  I found you were the only person that would stop me from cutting,  the only person that ever made me feel better about myself and my   47  . You don’t know this but I was trying to kill myself one night when you   48  me. I owe you so much, and you didn’t even know you were   49  me.” We both cried. And I guess a kind of lesson from my life so far is to never   50  your friends.

1.                A.pleased         B.excited         C.scared   D.disappointed

 

2.                A.happiness       B.kindness        C.shyness   D.sadness

 

3.                A.All            B.None           C.No  D.Every

 

4.                A.hardly          B.seldom         C.just  D.always

 

5.                A.neither         B.so             C.too  D.also

 

6.                A.mad           B.careless        C.hopeful   D.upset

 

7.                A.luckily          B.successfully      C.actually   D.calmly

 

8.                A.selfish          B.crazy           C.brave    D.lonely

 

9.                A.believed in      B.waited for       C.cared about   D.replied to

 

10.               A.with           B.after           C.upon D.to

 

11.               A.until           B.when          C.since D.if

 

12.               A.mistakes        B.parents         C.friends    D.problems

 

13.               A.visited         B.encouraged     C.called D.prevented

 

14.               A.helping         B.reminding       C.cheating   D.praising

 

15.               A.give up         B.look back at     C.drop in at  D.look down on

 

 

查看习题详情和答案>>

违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com

精英家教网