听力原文： There are four types of college degrees, starting with the associate degree. The associate take's about two years to complete when one is enrolled full time. The bachelor's degree takes four years when one is enrolled full time with the master's taking an additional one to two years, and the doctor's three to four years. The associate degree may be substituted for the first two years of a bachelor's degree if it is a transfer degree. Not all associate degrees are designed for transfer. Some are technical degrees which are called terminal degrees, which means they do not count toward a bachelor's. The bachelor's is normally required before one can work at the master's level. Likewise, the master is normally required before one can work at the doctor's level. The number of credit hours of university degree programs varies from one school to another. In general, the AA is 60 credit hours or 95 quarter hours. The BA (or BS) is 120 credit hours or185 quarter hours. The MA is 30 credit hours or 45 quarter hours and the PhD is 60 to 72 credit hours or 95 to 120 quarter hours. (30)