Câu hỏi:

Read the following passage, then choose the correct answer to questions.      

  The next generation of telephone users will probably laugh when we explain how we used to stand next to a wall in the kitchen to___(21)___ a phone call. Mobile communications, already highly advanced compared with a decade ago, will completely change communications in the next few years. ___(22)___ there are millions of people using mobile phones, most people know little about the mobile telecommunications industry and its technology. There are three types of mobile phone. These are hand portables, pocket- sized hand portables and transportables. The smallest and most popular are the pocket- sized hand portables. These work on rechangeable batteries, which allow an average on separate batteries. Mobiles that are fitted permanently in a vehicle do not___(23)___on separate batteries. They require an external aerial on the vehicle. This can mean a stronger signal with clearer___(24)____ . Transportables have a higher power capability and can be used___(25)___anywhere. They come with powerful battery packs for longer, continuous use and may also be put___(26)___ a vehicle, using its eletrics. They tend to be bulkier than hand portables.              The next generation of telephone users will probably laugh when we explain how we used to stand next to a wall in the kitchen to___(21)___ a phone call

       The next generation of telephone users will probably laugh when we explain how we used to stand next to a wall in the kitchen to___(21)___ a phone call.