既然很重要,所以在下是负责的,经过斟酌,鉴于中英的固有差异,就翻译成这个样子了：
It's been years since Mr.Zheng second's father was dead,but there wasn't any portrait as rememberance of the old man all these years long.
One day,he accidently met an old beggar who looked like his father very much.So with sincere words he managed to invite the beggar home as a model so that a painter could draw a portrait of his father（out of him）.
They came to an agreement that in addition to sufficient meals everyday,50 doits should be paid when the painting was completed,which the old beggar was very pleased to accept.
Then Mr.zheng second took out his nice clothes and the beggar put on them,then the painter began to draw according to him.
It was still underway when the beggar got a plot in his mind:"the clothes on my body must be worth at least several tens of silver,it would be fine if I can run away with these clothes and have a good survial of this winter."
Therefore the next day,after the outline was finished,the beggar asked to go for a pee,then he take the good chance and climb over the back wall and run away.