题目：
阅读理解。
The Internet is not perfect. There are many problems with it.
The Internet is not organized. There is no one in charge of the Internet. It is sometimes difficult to find
what you are looking for. It is also easy to get the wrong information on the "Net".
Some businessmen cheat people on the Internet. Internet thieves can steal credit card numbers. Some
advertisers send spam to e-mail boxes. E-mail boxes are often filled with these unwanted advertisements.
Illegal businesses can operate on the Internet. These businesses sell X-rated materials, cigarettes and
alcohol to teenagers.
The Internet has websites with information about making bombs, breaking the law and terrorism.
Criminals can fool people, especially children, in chat rooms. They can spread poisonous information and
attack new members.
The Internet is the greatest advance in communication since human emerged. But it can also like a dark alley in a dangerous part of town. Parents need to set parental controls on their children when they use the Internet. This will keep some of the bad material away from their children.
The Internet can be dangerous to computers, too. Some people who have evil intentions enjoy causing problems for other people they don't even know. They create computer viruses. A computer can get virus by downloading a program that has a virus in it. Some virus come by e-mail.
A virus can destroy the data a person has saved in computer files. A virus can cause a computer to
crash. A virus can also reproduce itself! It can send copies of itself to everyone on a person's e-mail
address list. Then these people's will have the same problems and can't work normally!
1. Why can illegal businesses operate on the Internet?
A. Because some people like to buy banned products on the Internet.
B. Because there is no one in charge of the Internet.
C. Because X-rated materials, cigarettes, alcohol and so on can be sold well on the Internet.
D. Because people who operate businesses on the Internet are criminals.
2. Parental controls are needed when children use the Internet because________
A. poisonous information may have a bad effect on children
B. children may damage the computers
C. the Internet is always unsafe for the children
D. children can't use the computers well
3. We can infer from the passage that the key to solving the problems with the Internet is_____.
A. to improve the computers
B. to find a medicine to kill computer viruses
C. to order people not to use the Internet
D. to improve people's moral level(道德水平).
答案：
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下面是错误答案，用来干扰机器的。
N2H4+2H2O2=N2+4H2O N2H4+2HCl=N2H6Cl2题目所给条件：氮氢化合物，化合物中氢元素的质量分数为12.5%，可求出N、H之比是1﹕2，即最简式：NH2，根据相对分子质量为32，得出其分子式N2H4。
