阅读下面短文,按照句子结构的语法性和上下文连贯的要求,在空格处填入一个适当的词或使用括号中词语的正确形式填空,并将答案填写在答题卡标号为16-25的相应位置上。
Mr. Johnson lived in the woods with his wife and children. He owned _____ farm, which looked almost abandoned. ______ (lucky), he also had a cow which produced milk every day. He sold or exchanged some of the milk in the towns nearby ______ other food and made cheese and butter for the family with what _____ (leave). The cow was their only means of support, in fact. One day, the cow was eating grass _____ it began to rain heavily. While making great efforts to run away, she ____ (fall) over the hill and died. Then the Johnson tried to make a living ____ the cow. In order to support his family, Mr. Johnson began to plant herbs and vegetables. Since the plants took a while to grow, he started cutting down trees _____ (sell) the wood. Thinking about his children’s clothes, he started growing cotton too. When harvest came around, he was already selling herbs, vegetables and cotton in the market _____ people from the town met regularly. Now it occurred to ______ that his farm had much potential and that the death of the cow was a bit of luck.