Here’s one number to keep in mind during your next cell phone conversation: 50. A new experiment shows that spending 50 minutes with an active phone pressed up to the ear increases activity in the brain. This brain activity probably doesn't make you smarter. When cell phones are on, they emit (发出) energy in the form of radiation that could be harmful, especially after years of cell phone usage. Scientists don't know yet whether cell phones are bad for the brain. Studies like this one are attempting to find it out.
The 47 participants in the experiment may have looked a little strange. Each one had two Samsung cell phones attached to his or her head — one on each ear. The phone on the left ear was off. The phone on the right ear played a message for 50 minutes, but the participants couldn't hear it because the sound was off.
With this set-up, the scientists could be sure they were studying brain activity from the phone itself, and not brain activity due to listening and talking during a conversation. After 50 minutes with two phones strapped to their heads, the participants were given PET scans.
The PET scan showed that the left side (the side with the phone turned off) of each participant's brain hadn't changed during the experiment. The right side of the brain, however, had used more glucose, which is a type of sugar that provides fuel to brain cells. These right-side brain cells were using almost as much glucose as the brain uses when a person is talking. This suggests that the brain cells there were active ― even without the person hearing anything. That activity, the scientists say, was probably caused by radiation from the phone.
Henry Lai, who works at the University of Washington in Seattle, is uncomfortable with the data related to cell phones. Holding a cell phone to your ear during a conversation is “not really safe,” Lai told Science News. Lai is a bioengineer at the University of Washington in Seattle. He wrote an article about the new study for a journal, but he did not work on the study. Bioengineers bring together ideas from engineering and biology.
For those who don't want to wait to find out for sure whether cell phones are bad for the brain, there are ways to talk more safely. You can have short and sweet conversations, use a speakerphone or keep the phone away from your head.
Which of the following statement is true?

A．Scientists are sure that cell phones are bad for the brain.

B．In the experiment, the left side of the brain used more glucose.

C．Radiation from the phone probably causes the change in the brain.

D．Henry Lai wrote a lot of articles about this new study.

Why weren’t the participants allowed to have a conversation on the phone during the experiment?

A．Because the scientists want to be sure of the accuracy of the experiment.

B．Because they really looked strange and no one wanted to talk to others.

C．Because they were given PET scans and they lost the ability to talk.

D．Because that would be too noisy and bad for the experiment.

What is glucose?

A．A type of sugar that provides vitamin to brain cells.

B．Something that the right side of the brain used.

C．A type of sugar that gives energy to brain cells.

D．Something that makes a human excited.

According to the last two paragraphs, which is the safest way to use a cell phone?

A．Holding the cell phone close to your head.

B．Using a cell phone more than three hours a day.

C．Taking the most powerful cell phone.

D．Keeping the cell phone at a distance.

Where is this article probably taken from?

A．Literature magazine.	B．Science News.
C．Story books.	D．Art Journal.

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