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Have you got a mobile phone?
Before mobile phones were developed, you could only call someone with a phone which was connected to a phone line. That problem meant that it was often difficult to contact people, particularly if you were on a bus or in a car.
Before mobile phones, people didn’t send text messages to each other. Since they were introduced, text messages have changed the way we communicate. With text messages, you don’t need to actually call someone. You simply type a short message and send it, being careful, of course, to send it to another mobile and not to a home phone.
Mobile phones used to be big and heavy. Now, they’re small and light. The chances are that they will become even smaller and lighter in the future.
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Before mobile phones, people didn’t send text messages to …
your friend
anyone
one another
each other