项目团队的核心要素包括人员、目标、互动、信任以及（）。 A.合作 B.文化 C.自愿

已知实数a，b，则a+b＞0是a＞0且b＞0的（　　）条件．

A．充分不必要

B．必要不充分

C．充要

D．既不充分也不必要

世界陆地最低点是________湖面，由于湖水含________量过大，除细菌外，其他生物不能生存。

第二部分阅读理解（第一节20小题，第二节5小题；每小题2分，满分50分）

第一节：阅读下列短文，从每题所给的四个选项（A, B, C, 和D）中，选出最佳选项，并在答题纸上将该选项标号涂黑。

Now as a mother myself, I'm anxious about the future, but I'm optimistic at the same time. I have the same concerns that my mother had for me and my brothers when we were growing up and going out into the world. The world it's said has shrunk or become flat. We're connected in ways we never were before. So how do we deal with these new challenges? Well, the other day I was speaking about my concerns for the future. And I said that I wanted to make sure that young people would work hard because we're in competition with jobs. When I was sitting where you are now, I didn't have to worry about competition from China or India. There were no global pressures like you will face as you mark your own way. And we need to get every young person to really get a sense of commitment and to work hard. Well, then my daughter said, "Mom I do work hard and my friends work hard." And I said, "I know that. I'm sorry, I didn't mean to convey any impression that you don't work hard. I just want to set the bar high because we are in a competition for the future."

You know, in 1999 when I was thinking of running for the Senate, I did not know what to do. I was really thinking hard because I had to make a decision. And there were a lot of things to consider. Obviously, no first lady had ever sought public office before. I had obviously never run for office before.

You know, often our most fearsome competitor is ourselves. We struggle with all of the internal doubts and anxieties, fears for the future, concerns for the world. Sometimes when I look at what's happening in the world, it's hard to imagine going out and doing anything of meaning. But we can do it and not only that, we must. America needs you to grab hold of this moment. So compete to do the best you can and help make our country the best it can be. So today, after you've accepted your diploma, but before you leave this place, please thank your family for guiding you to this moment. Thank your professors for showing you a new world. Thank your friends for exploring that world and finally remember what this day feels like. Cherish it always. Go for it. The world awaits you.

41．Who is most probably the speaker “I”?

A．a Chinese   B．an Indian   C．an American adult   D．a university student

42．Which of the following statements is true according to the passage?

A．Quite a few first ladies have run for public offices.

B．Only after you’ve got your diploma and before you leave your university should you thank your parents, your professors and your friends.

C．The speaker is always aware of what to do because she is a determined person.

D．The speaker is concerned about the future even though she is optimistic.

43．Why do you think the speaker urge the students to work harder?

A．Because the students are not really working hard at all.

B．Because they are faced with global competition on their way to their future.

C．Because only in this way can they afford to go to an expensive bar for a good drink.

D．Because their most fearsome competitors are themselves.

44．On the whole, the speech is ________ .

A．disappointing   B．encouraging   C．negative   D．necessary

“物竞天择、适者生存、优胜劣汰”的生物法则，最初出现在哪部书中[ ]

A．《天体运行论》

B．《物种起源》

C．《万有引力定律》

D．《自然哲学的数学原理》

过滤式自救器的使用时间为（）。

A、20分钟

B、30分钟

C、40分钟