【正确答案】
C
【答案解析】[听力原文] Today we will tell about one of the most recognizable objects in science field—the laser. It is one of the best examples of how technology can go from the science of the future to everyday use in a short period of time. The first medical operation using a laser took place the year following its invention. Doctors Charles Campbell and Charles Koester used a laser to remove a tumour from a patient's eye at Columbia-Presbyterian Hospital in New York City. Since then, doctors have used lasers to cut and remove tissue safely with little risk of infections. Other health uses include medical imaging and vision correction surgery. Energy researchers are using lasers in an attempt to develop fusion. Scientists hope fusion can supply almost limitless amounts of clean energy in the future. Lasers have also changed the way we communicate. Super-fast Internet connections let people watch movies and send huge amounts of information at the speed of light. Manufacturers have used lasers for years to cut and join metal parts. And the jewelry, industry uses lasers to write on the surface of the world's hardest substance, diamonds. Since 1947, the public has had direct experience with lasers—at the grocery store checkout line. Laser barcode scanners have changed how stores record almost everything. They help businesses keep track of products. They help in storage and every detail of the supply process. Experts say no company has put bar code technology to better use than Wal-Mart, based in Bentonville, Arkansas. By 1988, all Wal-Mart stores used laser bar code scanners. Highly detailed records on its products, and how they were selling, helped Wal-Mart keep costs down. Today, Wal-Mart is the world's biggest corporation. Lasers are found in many products used almost everywhere. Laser printers can print out forms and documents quickly and are relatively low in cost. They are required equipment for offices around the world. What does the passage mainly talk about? 题干问的是短文主要讲了什么内容。短文开头提到，激光是技术如何在短时间内从未来的科学发展到日常生活运用的最佳例证之一，接下来阐述了激光在医学、能源发展及其他领域的应用，在生活中随处可见。由此可知，短文主要讲的是激光在不同领域中的应用，故答案为C(激光在不同领域中的应用)。A项(激光在医疗手术中的应用)和B项(激光改变了我们的通讯方式)均是激光在日常生活运用的例子，不具有概括性，故排除。D项(激光在我们的生活中必不可少)短文中未提及，故排除。 预读四道题的各个选项，根据选项中的laser，medical operation，application，in different fields，printing等词可以预测，短文内容可能与激光有关，可能涉及激光在各个领域的应用等内容。