041.
Joe Jones was born in 1931. As a boy, he had a dream of becoming a doctor. But in 1948, when he was 17, he had to work to help to support his family. Joe worked in construction, on the railroad, and served in the army for over ten years. Then he worked in his hometown of Philadelphia for twenty years. But he still kept his dream of going back to school. In 1979, at the age of 48, Joe decided to make his dream come true. He finished high school and became a student in the Community College of Philadelphia, where he took all the math courses he could. In 1981, after a degree at the Community College, he was admitted to study computer in the University of Pennsylvania. In 1986, Joe completed his work on his master's degree. At the age of 56, Joe was studying for his doctor's degree. His dream was coming true.

答案解析：
(1) 正确答案为A。根据But in 1948, when he was 17, he had to work to help to support his family. 但是在1948年，他17岁那年，他不得不去工作以贴补家用。因此可知，约翰不得不去工作的时间是1948年，因此A项正确。
(2) 正确答案为C。根据he was admitted to study computer in the University of Pennsylvania. 他进入宾夕法尼亚大学学习计算机。因此可知，他在宾夕法尼亚大学学的是计算机，因此C项正确。
(3) 正确答案为B。根据Joe Jones was born in 1931. 乔·琼斯生于1931年。以及In 1986, Joe completed his work on his master's degree. 1986年，乔完成了硕士学位。可知，乔是在55岁时完成的硕士学位，因此B项正确。