题目内容：

able，alien，circle，express，might

mystery，outdoors，purpose，see，valuable

Crop circles(麦田怪圈)are patterns in fields that appear overnight.At first they were just some simple 76.1.，now the patterns have become very complicated(复杂的)．From a plane crop circles can look like a work of art 77.2.

Since the first crop circles were found in Britain in 1978，it has become a great 78.3.．How these crop circles are made？Who makes them？What is the 79.4. of making them?

Some scientists think that some of the crop circles 80.5. be man­made.They believe that thanks to modern technology，it is possible to create such complicated patterns in a short time.

However，others think that crop circles might be the work of some 81.6.．Because they often apper in areas shortly after there have been UFOs to be 82.7.．They also think that the circles are so complicated that nobody on earth is 83.8. to make a true crop circle.

Although different opinions about these crop circles have been 84.9.，one thing everybody agrees on.That is these crop circles are 85.10. to the local economy(经济)．Thousands of visitors come here to see crop circles every year.