阅读，回答问题
Mr. Green works in a shop. The shop sells，cleans and repairs（修理）hearing-aids（助听器）. One day an old man comes in and puts one down in front of him without（没有）a word.
“What’s the matter with it? ”Mr. Green says. The man doesn’t answer. Of course Mr. Green
thinks the man must be deaf（聋的）and something must be wrong with his hearing-aids（听力），so
he says again，more loudly，“What’s wrong with your hearing-aids，sir? ”Again the man says
nothing. So Mr. Green shouts his question again as loudly as he can.
The man then takes a pen and a piece of paper and writes，“It’s not necessary to shout when
you’re speaking to me. My ears are as good as yours. This hearing-aid is my wife’s，not mine. I
have got a throat operation（咽喉手术）. I can hear very well，but I can’t speak. ”
1. What does the shop do?
2. Why does the old man come to the shop ?
3. What’s wrong（什么毛病）with the old man?