什么是 fast?Acting, moving, or capable of acting or moving quickly; swift.Accomplished in relatively little time: a fast visit. Acquired quickly with little effort and sometimes unscrupulously: made a fast buck scalping tickets. Quick to understand or learn; mentally agile: a class for the faster students. Indicating a time somewhat ahead of the actual time: The clock is fast. Allowing rapid movement or action: a fast running track. Designed for or compatible with a short exposure time: fast film. Disposed to dissipation; wild: ran with a fast crowd. Flouting conventional moral standards; sexually promiscuous.Resistant, as to destruction or fading: fast colors. Firmly fixed or fastened: a fast grip. Fixed firmly in place; secure: shutters that are fast against the rain. Firm in loyalty: fast friends. Lasting; permanent: fast rules and regulations. Deep; sound: in a fast sleep. In a secure manner; tightly: hold fast. To a sound degree; deeply: fast asleep. In a rapid manner; quickly.In quick succession: New ideas followed fast. Ahead of the correct or expected time: a watch that runs fast. In a dissipated, immoderate way: living fast. Archaic Close by; near.To abstain from food.To eat very little or abstain from certain foods, especially as a religious discipline.The act or practice of abstaining from or eating very little food.