---Have you had lunch?     ----_____.

        A.Yes, How about you.   B.It’s very kind of you to invite me, but I’m afraid I hve no time.    C.Yes, why do you ask me?      D.All the dishes taste well.Thank you very much

---Have you had lunch?     ----_____.

        A.Yes, How about you.   B.It’s very kind of you to invite me, but I’m afraid I hve no time.    C.Yes, why do you ask me?      D.All the dishes taste well.Thank you very much

---Have you had lunch? 

---_____.

1. A.
   Yes, How about you.
2. B.
   It’s very kind of you to invite me, but I’m afraid I hve no time.
3. C.
   Yes, why do you ask me?
4. D.
   All the dishes taste well.Thank you very much

Ants have a reputation for strength,organization and teamwork.But researchers have now discovered that a key secret to the success of ants is their ability to identify the importance of age in the work place.
A study of Gentral American leaf-cutter ants has shown that the younger and stronger members are give the toughest job of cutting therough the leaves they harvest.Their sharp youn teeth do this job effectively,but as they get older their teeth become relatively worn and blunt.
But rather than being retired or abandoned by the group,the ageing ants are given a new role more suyted to their physical abilities.They become carriers and teansport the leaves back to the kingdom where they are harvested for food.
The findings by researchers from the University of Oregon and the Oregong State University support previous research showin the survival of a leaf-cutter kingdom depends on the efficiency(效率）of is workers.
“Cuting leaves is hard work,”said Dr.Robert Schofield,who led the research team.“Much of the cutting is done with a V-shaped blade(刀片）between teeth on their jaws.This blade starts out as sharp as the sharpest razor blade that humans have developed.”But over rime the teeth become blunter and the cutting job slows down.The team estimated that,because of this age-related wear,a colony(蚁群)spent twice the energy cutting leaves than it would if all the ants had sharp blades.Its findings support the idea that wear and break can be significant problems for insects as well as largre animals.
Like humans,leaf-cuttre ant recognize that older members of the group can still make a worhwhile contribution to society.“This study shows an advantage of social living that we are familiar with,”said Dr.Schofield.
【小题1】The younger and stronger ants do the toughest job because      .

完形填空（共20小题；每小题1.5分，满分30分）
阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
I teach biology at UNLV three times per week . Last Monday , at the beginning of class , I cheerfully asked my   21  how their weekend had been . One young man said that his weekend had not been so   22  . He had his wisdom teeth removed . Then he went on to ask me why I always seemed to be so     23  .
His question   24  me of something I’d read somewhere before : “Every morning when you get up , you have a   25  about how you want to deal with life that day .” I said . “I choose to be cheerful .”
“Let me give you an example ,” I continued ,   26  all sixty students in the class . “In   27  to teaching here at UNLY , I also teach out at a   28  in Henderson , 17 miles down the highway from where I live . One day a few weeks ago I drove those 17 miles to Henderson . I   29  the highway and turned onto College Drive . I only had to drive another quarter mile down the road to the college . But just then my car   30  .I tried to start it again , but the   31  wouldn’t work .   32  I turned my flashers on , took my books , and   33  down the road to the college .”
“As soon as I got there , I called and   34  for a tow truck to meet me at my car after   35  . The secretary there asked me what had happened . ” This is my   36  day .” I replied , smiling .
She was   37  . “What do you mean ?”
“My car could have broken down anywhere along the highway . It didn’t .” I relied . “  38 , it broke down in the perfect place : off the highway ,   39  walking distance of here . I’m still able to teach my class , and I’ve been able to get the tow truck to meet me after class . If my car was meant to break down today , it couldn’t have been arranged in a more convenient   40  .”
I ended my story . In spite of the early hour , no one in my class seemed to be asleep . Somehow , my story had touched them .