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(最新高科技设备). 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. Which picture is probably the one formed in the field behind the scientists?

2. “Flattened wheat” means ___________.

A. broken wheat B. lying wheat

C. harvested wheat D. growing wheat

3. 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