It is quite common these days to encounter people who speak very loudly into their cellphones in public areas. Like mobile phones themselves, this is actually a relatively recent development. “Haven’t people always shouted into their phone?” you may ask. Well, they __1__ this if they were angry, but not simply to make themselves heard. The main reason why people shout into their mobile phone is due to a fundamental design __2__ in the phones themselves.
Conventional telephones function in a similar way to the headsetsthat pilots[註]wear. While helicoptersand airplanes tend to be very noisy, you do not see the pilots shouting at one another. This is because their headsets are __3__ speakers and a microphone. When they speak into the microphone, they can be clearly heard by the other crew members with headsets. Not only that, but they can clearly hear themselves as well, since their microphone is connected to their own headset’s speakers. __4__, when you speak into a regular telephone, you can clearly hear your own voice in the earpiece.\
註：紙本雜誌上漏了 pilots 這個字，造成學習上困擾深感抱歉~~
This feature, known as sidetone, does not exist in mobile phones. Therefore, people only hear the sound of their regular voice when speaking into their phone. This causes many people to __5__ during a phone call, particularly if they are in a busy public area. Since the microphone is working just fine, however, there is really no need to do this.
1. (A) was doing (B) will do (C) are to do (D) might have done
2. (A) fault (B) virtue (C) model (D) threat
3. (A) adapted into (B) squeezed into (C) equipped with (D) charged with
