【正确答案】正确答案： Front A front is a weather system that is the boundary separating two different types of air. / Two major types of fronts are cold fronts and warm fronts. / Normally cold fronts come with thunderstorms or other types of extreme weather. / They usually move from west to east. / Strong, powerful cold fronts often take over warm air that might be nearly motionless in the atmosphere. / This movement is called a low-pressure system. / Warm fronts usually show up on the tail end of rain, snow, hail and fog. / As they overtake cold air masses, / warm fronts move slowly, usually from north to south. / Warm fronts are often associated with high-pressure systems. /