从方框中选择正确的单词并用其适当形式填空
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 1. ,now the patterns have become very complicated(复杂的).From a plane crop circles can look like a work of art 2. .
Since the first crop circles were found in Britain in 1978,it has become a great 3. .How these crop circles are made?Who makes them?What is the 4. of making them?
Some scientists think that some of the crop circles 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 6. .Because they often apper in areas shortly after there have been UFOs to be 7. .They also think that the circles are so complicated that nobody on earth is 8. to make a true crop circle.
Although different opinions about these crop circles have been 9. ,one thing everybody agrees on.That is these crop circles are 10. to the local economy(经济).Thousands of visitors come here to see crop circles every year.
1.circles 2.outdoors.3.mystery.4.purpose
5.might 6.aliens.7.seen.8.able
9.expressed 10.valuable