单选题 In the summer of 1978 an English farmer was driving his tractor through a field of wheat when he discovered that some of his wheat was lying flat on the ground. The flattened wheat formed a circle about six meters across. Around this circle were four smaller circles of flattened wheat. The five circles were in a formation like five dots. During the following years, farmers in England found the strange circles in their fields more and more often.
The circles are called "crop circles" because they appear in the fields of grain--usually wheat or corn. The grain in the circles lies flat on the ground but is never broken; it continues to grow, and 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.
At first, people thought that the circles were a hoax. Probably young people were making them as a joke, or farmers were making them to attract tourists. To prove that the circles were a hoax, people tried to make circles exactly like the ones that farmers had found. They couldn't do it. They couldn't enter a field of grain without leaving tracks, and they couldn't flatten the grain without breaking it.
Many people believe that beings from outer space are making the circles to communicate with us from far away and that the crop circles are messages from them.
Scientists who have studied the crop circles suggested several possibilities. Some scientists say that a downward rush of wind leads to the formation of the circles--the same downward rush of air sometimes causes the airplane to crash. Other scientists say that forces within the earth cause the circles to appear. There is one problem with all these scientific explanations: Crop circles often appear in formations, like the five-dot formation. It is hard to believe that any natural force could form those.

单选题 In the summer of 1978, an English farmer discovered in his field that ______.

单选题 According to the text, "a hoax" (Line 1, Para. 3) is probably ______.

【正确答案】 C

【答案解析】[精解] 释义题。题干意为“根据文章的意思，a hoax可能指什么?”文章的第三段中Probably young people were making them as a joke，or farmers were making them to attract tourists. 是对 hoax这个词的解释。“年轻人开的玩笑”和“农民们为了吸引游客自己做出来的”当然都是“恶作剧”。所以正确答案选C。

单选题 Which of the following may prove that the crop circles are not made by man?

【正确答案】 A

【答案解析】[精解] 推断题。题干意为“下列哪一项或许能够证明这些庄稼圈不是人类造的?”文章第三段最后一句话说They couldn't enter a field of grain without leaving tracks，and they couldn't flatten the grain without breaking it. 即人们不可能进入庄稼地而不留下任何踪迹。所以本题的正确答案为A。