题目内容：

Maybe you think that many parents have a lot to learn about what their children are doing online. According to a recent survey by Symantec Company, which makes many kinds of security(安全)software for home and business computers, there's a "huge difference between parents and their kids".

Parents of children under the age of 18 were asked to estimate(估计)how much time their kids spent online each week. The parents said about three hours a week on average(平均).The kids－ages 8 to 17－who took the survey said they were spending an average of seven hours online each week.

"I really think that's because of the time they spend on their mobile phones and computers, when their parents don't even know they're online," says Symantec's Bill Rosenkrantz. "Remember, cellphones, PDAs and video game machines all make it possible to surf the Internet. You don't have to sit in front of a computer screen."

And what are the kids doing on the Web? "They're doing things, like downloading music, they're going to social networking sites, they're actually shopping online when parents don't think they're doing those kinds of activities," says Rosenkrantz. "They're also, we think, doing some things with research papers and other kinds of activities with homework maybe where  they're getting some information online and they really shouldn't be." Nearly a quarter of the kids (23 percent) night do things their parents would not agree.

So how does a modern parent deal with this type of situation? "The first thing we strongly recommend is that parents spend fine with their children online," Rosenkrantz， says. "Sit down with them and understand what they're doing. Secondly, have a dialogue about it. Have a dialogue about what's an acceptable activity, what's an unacceptable activity, and set some ground rules－time online, things you can and can't do. Really have those conversations. That's the most important ." There are a lot of bad people on the Internet. That's why it's so important for parents to know what their kids are doing online.

1.The data(数据)in the second paragraph are used to show       .

A. parents don't exactly know kids' online activities

B. time spent online changes with children's ages

C. children always spend too much time online

D. children spend more time online than their parents

2.What can we learn from the passage?

A. Some kids surveyed may go against their parents' rules.

B. Most parents know what their kids are doing online.

C. Special home computers are being made by Symantec.

D. Parents are too busy to pay attention to their kids.

3.In Rosenkrantz's opinion, the key to the situation is that parents should       .

A. shorten their kids' time spent online

B. know their kids' online activities

C. use security software in computers

D. have a dialogue with their kids

4.What's the purpose of the passage?

A. To advertise a piece of useful security software.

B. To call parents' attention to kids' online behaviour.

C. To warn children of the risks online activities.

D. To give reasons for kids' bad Internet habits.