题目

Internet access and power outlets available in most cafes in the．developed world might reduce your productivity． A typical tale from store managers is of customers who buy a single cup of coffee or tea and occupy a four-seat table for eight or more hours．A store full of these people turns the shop into a silence broken only by the tapping of keyboard keys．In others, however, customers use the network briefly, and the turnover is high． Cafe owners have talked about their discomfort for years．Some cafes founders started turning off Wi-Fi （无线网络） on the weekends．The烛焰通过凸透镜恰好在光屏上得到一个缩小倒立的像，若保持透镜位置不变，把烛焰和光屏对调一下，则（ ）A．光屏上仍能呈现一个缩小的像B．光屏上呈现一个放大的像C．光屏上不能呈现出像，但通过透镜用眼睛可以看到D．光屏上呈现一个等大的像