one－year-old前面用an还是a

one－year-old前面用an还是a one-year-old boy 前面是填a还是an呢? 是a one-year-old boy还是an one-year-old boy 18—year—old前面用a还是用an three-year-old boy 这样的前面用a还是an?两种我都看过.. year前面用a 还是用an （a/an）18-year-old 18前面是an还是a an onehundred-year-old man用a还是an 当an eleven-year-old girl中eleven是数字11时用a还是an当an eleven-year-old girl中eleven是数字11时前面用a还是an a eleven-year-old还是an eleven-year-old 是a eight-year-old 还是an eight-year-old Tim is ____boy.He can say a few words.A.an one-year-old B.a one-year-old C.an one-year oldD.a one-year old she is an 8-year-old girl 和she is a 8-year-old girl 到底前面是an 还是a a one-year-old boy为什么不是an Tom has( ) one-year-old brotherA a,B an - Though Mike is ( )boy,he can say many words.--How cleverA.an-one-year-old B.a one-year-old C.an one-year old D.a one-year old Tim is ___ boy.He can say a few words.A.an one-year-old B.a one-year-old C.an one-year oldD.a one-year old 形容词+one前面用the 还是 a/an比如说 beautiful one useful one