閱讀測驗    Smartphones, which are usually equipped with(配備有) touchscreens and powerful operating systems (作業系統), can do a lot of things. In addition to those basic features such as making calls and sending messages, smartphones allow users to check e­mails, watch videos, and even locate (定位) their positions. They are like personal computers, only more portable. Since most smartphones are light and small in size, users can take these devices with them no matter where they go.    One important feature of smartphones is the app (應用程式). Smartphones are able to run a wide variety of apps, including games, education apps, banking apps, and so on. With smartphones, users can run apps either just for relaxing or for fun learning—or both. They can also check their bank accounts on their portable devices anytime rather than at banks during open hours. What’s more, there is an app that can talk and help do a lot of things on smartphones like a real person. By speaking to their smartphones, users can give a call or write a message without touching their phones.    To make apps and other features work well on smartphones, faster speed is needed. Therefore, engineers keep on developing high technology, designing better microchips and hardware. Customers have to pay high prices for these high­tech products. Nevertheless, providing much entertainment (娛樂) and convenience, these all­in­one devices have attracted more and more users every year. Smartphones have made the modern world a “smarter” one.
【題組】31.( ) What is the passage mainly about?
(A) The history of smartphones.
(B) A simple introduction of smartphones.
(C) The development of recent microchips and hardware.
(D) The functions of different apps on smartphones.