4.听短文回答问题:下面你将听到一篇短文及五个问题,根据短文内容从各题的三个选项中选出一个正确答案.(录音播放两遍) 16.A.The first floor. B.The second floor. C.The fourthfloor. 17. A.Technology in the old days. B.Inventions in different centuries. C.Modern inventions in the 20thcentury. 18.A.On the first floor. B.On the second floor. C.Onthe fourth floor. 19.A.Searching the Internet. B.Asking theguide for help. C.Buying books ormagazines. 20.A.A guide. B.A teacher. C.A worker.