In the summer of 1978 an English man named Steven was driving his tractor through a field of wheat
when he discovered something strange. Some of his wheat was lying on the ground. The flattened wheat
formed (形成) a circle about six meters across. Around this circle were four smaller circles of flattened wheat.
     Three years later a farmer who lived nearby discovered almost the same circles in one of his fields. These
circles were larger-nearly 15 meters across. That same year, another English farmer discovered three circles
of flattened wheat on his land-one large circle between two small circles. During the following years, farmers
in England found circles in their fields more and more often.
     The circles are called "crop circles" because they usually appear in fields of wheat or corn. The wheat in
the circles lies on the ground but is never broken; it keeps on growing, and the farmers can later harvest it.
Farmers always discover the crop circles in the morning, so the circles probably form at night. They appear
only in the months from May to September. What causes the crop circles?
     At first, people thought that some kids were making them as a joke, or that farmers were making them to
attract tourists.(In fact, in 1991, two men said they made the circles themselves, but many scientists don't
believe them.) People tried to copy them: They tried to make circles exactly like the ones the farmers had
found. They couldn't do it. They couldn't enter a field of wheat without leaving tracks, and they couldn't
flatten the wheat without breaking it.
     Several times people reported seeing stranger objects near the fields where crop circles later appeared.
Many people believe that these crop circles are the messages sent by living things from outer space (外層空間) or the marks left by their spaceships.
     Scientists who have studied the crop circles try to find out what causes them. In the summer of 1990
some scientists spent three weeks in the part of England where many circles have appeared. They had all the
latest high-tech equipment (最新高科技設(shè)備). The equipment-worth 1.8 million dollars-got nothing. But one
night, as the scientists were watching a field, crop circles formed in the field behind them, which were quite
different from the others. The scientists had neither seen nor heard anything.
     When Steven discovered the crop circles on his land in 1978, he said, "It was just like something that had
landed in the field from the air and gone back up again. I don't know what to make of these things."
     Crop circles have appeared in England, Japan, the United States and Russia. Experts from all over the
world have studied them, and they say what Steven said: They don't know what to make of these things.

1. "Flattened wheat" means ___________.

A. broken wheat
B. lying wheat
C. harvested wheat
D. growing wheat

2. The passage is mainly about something ___________.

A. that is done by living things from outer space
B. that cannot be solved but found all around the world
C. that cannot be made clear or understood
D. that is discovered and copied by the farmers

        Wearing the wrong type of glasses will do harm to your eyes. This
is not true for adults, although incorrect glasses may not be good for
children under 10. Ready-made glasses, and not wearing when you
should, won't do harm to your eyes, but you may see better with glasses
that are specially made for you.Watching too much television is bad for
your eyes. This is not true. People with easily affected eyes may find
they get red and aching from staring at a fixed distance for long periods,
but there won't be any lasting effects.Carrots will help you see in the dark.
Carrots are rich in beta-carotene, which the body can change into vitamin
A, too little of which can cause night blindness. However, people in
most countries don't need to worry about vitamin A deficiency (缺乏)，
night blindness is more likely to be connected with another vision problem.

1. According to the passage, which of the following is TRUE?

A. Ready-made glasses will do harm to one's eyes.
B. Wearing the wrong glasses may do harm to children's eyes.
C. The human body is unable to change beta-carotene into vitamin A.
D. Watching less television may do harm to children's eyes.

2. Night blindness is most likely caused by _____.

A. staring for long periods
B. too much beta-carotene
C. not enough vitamin A
D. vision problems