题目

There are three airports in New York.When you arrive at one of them,you can take a bus or taxi to any place in New York. Public transport  In New York there′s a good bus and subway service.If you are planning to use the subway a lot ,you should buy a subway ticket for ten tours because it′s cheaper.But you don′t have to use public transport-there are lots of places you can go to on foot,like the Empire State Building,5th  Avenue and Central Park.The New York taxis are a part of the city experience,so you should take at least one taxi during your visit! Hotels  There are lots of小明同学在光具座上做“研究凸透镜成像”的实验．当烛焰、透镜及光屏的相对位置如图所示时，恰能在光屏上得到一个清晰的像．由此判断，他所用的凸透镜的焦距（　　）A．一定小于8cmB．一定大于20cmC．一定在8cm到10cm之间D．一定在10cm到16cm之间