一个三岁大的孩子：a three-year old baby a three-year-old baby 到底应该是哪个

一个三岁大的孩子：a three-year old baby a three-year-old baby 到底应该是哪个 the baby is one and a half _____ (year)old three years old 与 three-year-old 的区别 a three－year－old boy,可以说成a three years old three-year-old triplet 的意思 three-year-old boy 这样的前面用a还是an?两种我都看过.. ( ) 1.My little sister is only .A.three year old.B.three yea three-year-old 和 three years old 有什么区别 three-year-old 与 three years old区别 three -year-old 和 three years old有什么区别? three-year-old这类词算哪个语法点 The baby is three months old.It has only a little____.A,teet