半价用英语是at a half price 还是没有a

半价用英语是at a half price 还是没有a at half a price/at half price/at a half price哪个是对的哪个是错的...为什么 “半个月”用英语怎么说?是half mouth?还是half a mouth?还是half of mouth?还是half of a mouth? 为什么7:30是half past seven.而不是at a half past seven 一年半用英语怎么说?是one and a half years还是one and a half year? in half a price还是 at half a price? 一个半小时 英语：是one and a half hour 还是 one and a half hours 急用!英语连词成句is game eight therer baskerball past evening at a this half 问一个简单的英语用法.I bought a pair of shoes_____a.at the half priceb.at half the price这应该是属于一个用法问题 ·· A:_____? B:About two and a half months.A When are you leaving for Shanghai?B How long have you been at this school?如果是B,时间段应该用FOR呀!!FOR TOW AND A HALF MONTHS!! At half past six是何意思? 英语里“一半”究竟是用one half 还是 half one表达? 是in the half-time 还是on the half-time 还是at 他和half time 是in the half-time 还是on the half-time还是at the half-time 一道微观经济问题,应该.A monopolistically competitve profit-maximizing firm is producing and selling 2000 units of output.At this output level,marginal revenue is $9,average revenue is $10,and the average variable cost is $8.The product pric a half 是多长时间.谢谢 has a bath six on the Moon past at half Tom (用这些单词组成一句话) ---when do you usually go to bed at night?----at ( ) eleven.half past,a half past,half hour pasta half hour past,为什么选a