题目内容：

明那,i can't buy that kind of book,beacuse they——out the day before yesterday.
我本人认为，填 had been sold.但老师说不行，有答得好的我再给分

优质解答

答案：were sold
be sold out意思是“被售光/完”,句中时间状语the day before yesterday“前天”表明句子只能用一般过去时,所以是were sold out.