【正确答案】
There are many explanations for why UFOs visit the earth. The most popular one is that they may be visitors from other planets. To fly such aircraft, their builders must develop different forms of aviation, because they seem to fly much faster than normal aircraft. The UFOs, it is believed, must contain scientists from other planets who are studying life on earth. It is even believed that several such aircrafts may have landed on earth and the space visitors may be living among us.
But there are also less fantastic explanations available. Although some sightings of UFOs are difficult to explain, most can be explained quite easily. In many cases the observers might have made a mistake. They might have seen a weather balloon or an aircraft. Or the light they saw in the sky might have been light from the ground, reflected on the clouds. However, the exact cause of many sightings still remains a mystery.

【答案解析】[解析] 此篇听写的关键词为UFOs，注意把握与主题相关的planets，aircraft，a weather balloon等词。 由首句可知这篇短文解释了不明飞行物拜访地球的原因。 may be中的be是表示判断的系动词，不要连写成maybe。 词以类记很重要。 第二遍听音时，将句型结构记下来。 difficult to之间不完全爆破。 made a之间连读。 有weather balloon“气象气球”的背景知识，就不会把weather写成whether。