in a day or two与in one day or two的区别?"He will be back in a day or two"为什么不能说"He will be back in one day or two"?

in a day or two与in one day or two的区别?He will be back in a day or two为什么不能说He will be back in one day or two? 单选You can return the book in _____.You can return the book in _____.A one or two day B one day or two C a day or two D one day or two days为什么? I'll be back in __________a one day or twob a day or twoc a or two daysd one day or two days选哪个？为什么？ I’m sure that he will be back in ____.A.a day or two B.one day or two C.a or two days D.one or two day选哪个?为什么? Come and see me in ( ) A, two or three day's B,two or three days' time 翻译一下 The librarian asked him to return the book_____A.in one day or two B.for one or two days C.within one day or two days D.in a day or twoA 和C为什么不对 I‘ll come to see you ___________选B对了吗A .in a day and two B.in a day or twoC.after a day or two D.after one or two days they will return in a or two day.把这个句子重新组装一下 I'll come round in a day or two.中的round在句中做什么成分, in one day or two有语法错误吗 英语中a 和one有什么区别?例如my friend will return in _____.A.one day or two B.a day or two C.one or two day这题选择B谁能给解释下. come and see me in in two or three days' time为什么 in two or three day’s time,不对 more details will be emailed to you in amore details will be emailed to you in a day or two. in two day's I'll go to see you in a day or two怎么翻译?这里的借此为什么用or? in one or two a two-day holiday 与in two years' time有何区别? John was ill ,so he had to stay in bed for ( )A.one day and two days B.a or two days C.a day or two D.one and two