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                                                                Fresh Air will Kill You

    Smog, which was once the big attraction of Los Angeles, can now be found all over the country from

Butte, Montana, to New York City, and people are getting so used to polluted air that it is very difficult

for them to breathe anything else.

    I was lecturing recently, and one of my stops was Flagstaff, Arizona, which is about 7,000 feet above

sea level. As soon as I got out of the plane, I smelled something peculiar(奇怪的). "What's that smell?" I

asked the man who met me at the plane. "I don't smell anything," he replied.

    "There is a definite odor that I am not familiar with," I said.  

    "Oh, you must be talking about the fresh air. A lot of people come out here who have never smelled

fresh air before." "What's it supposed to do?" I asked suspiciously.

    "Nothing. You just breathe it like any other kind of air. It's supposed to be good for your lungs."

    "I've heard that story before," I said. "How come if it's air, my eyes aren't watering?"

    "Your eyes don't water with fresh air. That's the advantage of it. Saves you a lot in paper tissues."

    I looked around and everything appeared crystal-clear. It was a strange sensation and made me feel

very uncomfortable.

    My host, sensing this, tried to be assuring. "Please don't worry about it. Tests have proved that you

can breathe fresh air day and night without its doing any harm to the body."

1. What is the air like in Flagstaff?

A. Polluted.    

B. Fresh        

C. Dirty          

D. Clean

2. We can infer from the story _______ .

A. Flagstaff is a small city

B. fresh air made the writer sick

C. the air in many American cities is polluted

D. breathing fresh air day and night does you no good

3. How did the writer feel when he first came to Flagstaff?

A. Excited    

B. Disappointed    

C. Uncomfortable  

D. Surprised

集合{，1，4，9，16，25}用描述法来表示为______．

何谓真空热处理，有何优点？

软件概要设计的成果是______。

运输和储存是物流系统的两大支柱，物流过程中其他各环节的活动都是围绕着运输和储存而进行的。