It seems that many parents have a lot to learn about what their children are doing online. According to a recent survey by the Symantec Corporation, which makes many kinds of security software for home and business computers, there’s a “significant digital（数字的）divide 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. The kids – ages 8 to 17 – who took the survey said they’re spending an average of seven hours online each week.
“I really think that’s due to 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, cell phones, PDAs and video game machines all make it possible to access 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 content online and they really shouldn't be.” Nearly a quarter of the kids (23 percent) admit to doing things their parents would not approve.
So how does a modern parent deal with this type of situation? “The first thing we strongly recommend is that parents spend time with their children online,” Rosenkrantz says. “Sit down with them and understand what they're doing. Secondly, have a dialog about it. Have a dialog 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.
The figures 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

We can learn from the passage that _______.

A．some kids surveyed may go against their parents’ rules

B．kids talk less with their parents due to computers

C．special home computers are being made by Symantec

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

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 talk with their kids

What's the purpose of the passage?

A．To advertise a new security software.

B．To give a short introduction to a survey.

C．To warn children of the danger online.

D．To give reasons for kid's Internet addiction.