in half a price还是 at half a price?

in half a price还是 at half a price? 是at a low price 还是in a low price at half a price/at half price/at a half price哪个是对的哪个是错的...为什么 半价用英语是at a half price 还是没有a 价格合理是at a good price还是at good price at a good price 还是 for a good price buy with OR at?I bought rhese jeans___in the sale.A with low price B at half price 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 以很低的价格用英语怎么说是in a low price还是at? 以很低的价格是in such a low price 还是at such. 什么a very good price,in,at with还是for,急如题 only students can get it at half price. 同义句 you can get it at half price ——— —— a student “on”能与“price”搭配吗?比如：in a lower price 还是 on a lower price at a price at a price同义词 at a good price （）allow the vegetables to go bad,he sold them at half price?（ ）allow the vegetables to go bad,he sold them at half price? A.In order to B.rather than C.Instead of D.Not to 请选出正确选项,说明原因,并说明其他不选的理由.谢