The missing boys were last seen ___ near the river.

A. playing  B. to be playing  C.play   D. to play

You might as well ___ him alone no matter what he will say.

A. to leave   B. forget   C. leave   D.to forget

If I ___ free tonight, I'll go to the cinema with you.

A. an   B. was   C. will be    D. be

— Was her concert a great success?

   — Sure. _______ such a good chance, how could she let it slip away?

       A．Having given          B．Giving     

       C．Having been given   D．Being given

Targeting teens

But using the Web also makes teens a target. Posting too much personal information for those millions of cyber eyes to see can cause some big problems and can even invite a threat to your life.

As Mary learned, not everyone on the Internet is who he or she says they are. Adults will sometimes pose as other teens, posting fake photos and nice messages to gain trust. They use their fake identity to access the personal information of others, such as home address, phone number, or school name.

"That's not the most common scenario", says David Finkelhor, a sociology professor at the University of New Hampshire. "Only 3 percent of teens aged 10 to 18 who use the Internet report being asked to meet offline. But the danger is real.

Safety measures

Mary's My Space profile is set to "private", which means that only the people she adds under the "friend" category can access her page. She also doesn't have any pictures of herself on her site. The only self-identifying material she has posted is her name, grade, and a list of hobbies.

"People can only add me if they know my last name or my e-mail, "Mary says. " I don't want random people to see my profile. I just go online to talk to my friends."

Stay safe and have fun online

Experts say almost 90 percent of U.S. Teens are online. But not everyone knows how to surf the Web in a smart way. With these tips, you can have fun, stay safe, and avoid embarrassment!

Pick a safe password. Make sure your password is something that other people won't be able to guess. Use numbers in between letters. "spar123ky" is better than "sparky 123."

Pick a safe username. Make sure yours doesn't say too much about you, "Happygirl13" is better than "AliceWaters13." Don't include your name, age, or where you are from. Never tell a stranger your name, school, address, age, birthday, phone number, or friends' names.

56．Who is most likely to be a victim online?

     A．A liar.      B．A teenager.       C．A stranger.      D．An honest person.

57．In Mary's opinion, _________.

     A．one shouldn't trust everyone online B．one shouldn't trust anyone online

     C．there are many liars online      D．all people online pretend to be others

58．One of the safety measures mentioned in the passage is that _________.

     A．one should not chat with strangers

     B．one should not post his or her photos online

     C．one should tell his parents about strange information

     D．one should keep his web as a secret

59．Why are numbers used when we pick a safe password?

     A．Numbers are easy to write.

     B．Using numbers are cool online.

     C．The safe password is more unlikely to be guessed.

     D．Numbers are popular online.

I would love ___ to the party last night but I had to work extra hours to finish a report.

A. to go   B. to have gone   C. going    D. having gone

—I’m going to travel to America. Would you consider telling me about your experiences there?

       —______. Let’s discuss it over dinner.

   A. That’s all right     B. By all means       C. Go ahead        D. It just depends

Without facts , a person can’t form a correct opinion , for he needs to have actual knowledge           his thinking .

       A．which to be based on      B．on which to base    

       C．which to be based   D．which to base

________ people with mental－health problems want most of all is a more equal and open working culture.

A．That  B．What C．When       D．All what

Questions and exercises  are given by the computer, which decides ______ to move the students ahead, review an easier level, ____ give more work on the same level.

   A. either, or    B. both, and    .C. whether, or     D. not only, but also