an hour and a half或者 one and a half hourstwo hours and a half/two and a half hours用is,因为时间不可数,虽然小时可数:离天亮还有两个半小时。It was two and one-half hours to dawn.你的展示预定在一个半小时之后开始。Your demo is scheduled to start in an hour and a half.世海明天要/会学中文学一个半小时。Tomorrow Shihai will study Chinese for one and a half hours.