1990年8月，某远洋客轮上一起军团病爆发流行。船离开港口时载有350名乘客、50名船员。8月1日前的一周内，在一次风暴中有1/7的乘客遇难。8月份第一周中，船上有30人发生军团病，其中一半很快死亡。随后的一周内又有20人发病，但无死亡。假设症状持续一个月，8月14日军团病的患病率是（）。

A.0.104

B.0.075

C.0.143

D.用该资料不能计算

E.以上答案均不是

To get help, Internet addicts tired of their square-eyed, keyboard tapping ways need look no further than the Web for counseling. There is now an online counseling service at www. relate, org. nz for Internet obsessives. Just e-mail the details of your Internet-induced crisis and help comes direct to your inbox. (46)The new breed of cybertherapists see nothing strange about offering help through the very medium that is swallowing their clients’ free time and splitting their marriages.
Getting hooked on the Internet isn’t confined to a few computer nerds. It’s on the rise everywhere—and women are the most likely addicts. The old stereotypical addict was a young man who spent hours playing games, downloading software or reading messages on newsgroups. (47)Yet, the new image is of a young woman who fritters away hours e-mailing friends, buying books and CDs online, talking in chatrooms and looking for information for next year’s holiday.
Ingrid Parker, once a slave to Internet chatrooms, found her experiences so devastating that she wrote a book to help other addicts break the habit. (48) Her computer dream turned to nightmare when she sold up and moved to be with her cyberpal (who had just left his wife), only to be told a week later that the couple were getting back together. The heart-breaking turn of events gave her the motivation to control her addiction—and write the book Caught in the Web.
For Ingrid Parker, anyone who is married or in a sound relationship should not really be spending hours talking to someone else and ignoring their nearest and dearest. (49)While Parker provided her own therapy by putting her experiences down on paper, she recommends others take up the online counseling offer, or log off from the Worldwide Web gradually.
She said, "It’s like smoking. It’s not a good idea to suddenly go cold turkey. People often e mail me about the problem and I tell them to gradually wean themselves off and not to switch to a scheme where you pay per hour for online time. (50)If they break their resolution, all they end up with then is the same old problem plus money difficulties for the long hours they have spent logged in to the Internet. "
Of course, the Internet is definitely addictive but if you can keep it in control it has advantages, too. Using it can be a steep learning curve so it helps you become very quick at learning. Also there is a huge demand for people in the field of Information Technology (IT) and hours on the Internet are great training.