A married couple were very worried about their son. Though normal（正常）in other way, he seemed to be dumb（哑的）. Not once had he spoken and now he was six years old. They had tried everything to get him to speak, but with no success.

　　The finest doctors in the country had examined him, but could find nothing wrong with his throat（喉）, and he seemed to be a very clever child. It was just that he never spoke.

　　“It's possible,” one of the doctors said. “There is something wrong with his mind, and he does not understand that he is capable of speech.”

　　“But he can read and write,” the boy's father said. “Perhaps he will grow out of his silence one day.”

　　The years passed. The boy left primary school and went to secondary school. He left secondary school and went to university. But he did not speak a single word.

　　Then one day, during a summer vacation, he was sitting at the dining table having a meal with his parents. Without any warning, he looked up from his meal and said, “Pass me the salt, please.” His parents were overjoyed.

　　“You spoke! You spoke!” they cried. “Why have you waited so long to speak?”

　　The young man looked at them and said, “I didn't have anything to say, until now everything has been perfect. But you obviously（明显地）forgot to put salt in these potatoes.”

(1) The couple was worried because their son ________.

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(2) They had great ________.

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A．success in getting him to speak

B．trouble in getting him to speak

C．fun listening to their son

D．problems listening to their son

(3) The doctors decided that ________.

[　　]

A．there was something wrong with the boy

B．they could help the boy

C．the boy was unable to say anything

D．the parents should write to their son

(4) Although the boy didn't speak ________.

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(5) The boy spoke because ________.

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A．he had a complaint about his food

B．everything was perfect

C．his parents were surprised

D．he wanted to eat