根据短文内容，用方框中所给单词的适当形式填空，每词限用一次。

    A farmer was put in prison (监狱). One day, he got a letter from his wife. "I am worried about our farm," she wrote. It's time potatoes, but I can't do all the by myself." The farmer then had an idea. He wrote to his wife, "Don't dig the fields. This is my gold (金子) is." A few days later, the farmer got the letter. It said, "About ten guards (守卫) came to our farm. It they were looking for something. They dug our farm everywhere." The farmer wrote to his wife at once. "Now you can plant our potatoes," he wrote.