在八年级英语北师大版第一单元中有下列句子
Lastweek,weaskedreaderstotellusaboutwhattheydidinthesummer.Herearesomeoftheirreplies:
Inthesummervacations,Istayedwithmyuncle.
但之前学过“在夏天”只能用"insummer",中间是不能加冠词的;还有下面的"inthesummervacations"不应该是"insummervacation"吗?很是不解,请给予解释,