为什么四点十五是a quarter past four

为什么四点十五是a quarter past four 十二点十五英语怎么说twelve a quarter这么写对吗 three quarter of a book为什么quarter没用复数 quarter 已经是一刻钟的意思了,为什么a quarter to seven.前面还要加一个a呢?回答要详细点、不然我不能理解 a quarter after eight 是几点钟? 下午三点一刻,晚上四点四十五,九点四十五,二点二十五,五点五十,以上用英语怎么说（用past,to,quarter）说 three quarters of a million or one and three quarter million 为什么一个quarter加s一个quarter没有s they arrived a quarter to eleven.a quarter to eleven前为什么没有加at 为什么half前不加a而quarter前加a 8点45分是quarter to nine还是a quarter to nine 3点45是“a quarter to four还是quarter to four It's a quarter past ten和It‘s half past ten为什么quarter前面加a ,half不加? have sport at a quarter Past four.It's quarter past eight 为什么前一个用a,后一个不用 a quarter怎么翻译 a quarter to a quarter past a quarter after At a quarter past