单项选择题

Mr. Long was only thirty but drank for thirteen years. He spent much time in the restaurants and often drunk a lot there. He had a rich sister who often supplied him enough money. So he was never worried about food or clothes.
Once a young man began to work in his company. They met at a party and introduced themselves to each other. Mr. Long knew his name was Mr. Kidd and he came from another city. The young men liked to drink too and they became good friends. They always met in the restaurant at weekend and didn’t leave there until they were drunk. Of course it was bad for their health. Their friends advised them to stop drinking, but they didn’t listen.
It was Saturday again. Mr. Long called his friend and they decided to spend the evening in the restaurant. Mr. Kidd agreed to his opinion and got there in time. They drank one glass after another and they didn’t stop until the men in the restaurant refused to sell the wine to them. They came out together and sat down at the side of the street.
Pointing at the moon, Mr. Kidd said," Your sun is smaller than ours!"
"We have a bigger one,’ said Mr. Long "But I wouldn’t show it to you. "
"I’ll buy it for all the jewelry in world , "called out the first drunkard(醉鬼).
"What makes you think I’ll sell it to you" the other drunkard asked in reply(反问).
Mr. Long began to drink when he was ______ .