阅读理解。

     Have you seen Avatar (《<阿凡达》)?

     It's a popular movie this year. It is three-dimensional (3D), so you may have to wear a special pair of

glasses to see it. The 3D glasses make the images (图像) from the movie look like they are coming straight

at you.

     More and more 3D movies are coming to theaters. Some say that 3D TV sets will come into our homes

in the near future. Three-dimensional technology can make TV and movies more exciting. But people with

eye problems may get headaches if they spend too much time watching 3D movies. Why?

     When we look at an object, each eye sees it at a different angle (角度). Our eyes send the two images

to our brain, and the brain puts them together. That' show we see depth.

     Three-dimensional technology uses two film projectors (投影机). One projects a left eye image and the

other projects a right eye image. 3D glasses allow us to see a different image in each eye.

     There are a lot of people walking around with very small eye problems, for example an eye muscle

imbalance. Under normal situations, the brain can get used to their eyes so they can see things normally.

     But when they are watching a 3D movie, the images projected to their eyes can't be put together by their

brain.

     So the brain needs to work harder at "reading" the images. That makes it easier for these people to get

dizzy or develop headaches.

     Dr John Hagan, an eye doctor in Kansas City, said some people who do not see depth normally cannot

see in 3D at all. He said people whose eyes can' t focus on (聚焦) the same object at once will have trouble

seeing 3D images.

1. When we wear a pair of 3D glasses, _____.

A. our brain will get a different image from each eye

B. our brain will put the different objects together

C. our eyes will focus on the same object easily

D. our eyes will see an object at the same angle

2. What does the underlined words "normal situations" mean?

A. When people see things normally.

B. When people have no eye problems.

C. When people don't have a headache.

D. When people aren't seeing a 3D movie.

3. What does the writer want to tell us in this passage?

A. Seeing 3D movies can bring us eye problems.

B. Not all the people can watch 3D images.

C. The 3D glasses make the movie seem alive.

D. The 3D movies will be very popular soon.