an 8-month-old boy为什么用an?

an 8-month-old boy为什么用an? James is ________ boy.A.a 18-month-old B.a 18 months old C.an 18-month-old D.an 18-months-oldJames is ________ boy.a 18-month-old B.a 18 months old C.an18-month-old D.an 18-months-old _____(a/an)1-year-old boy _____(a/an)8-year-old boy _____(a/an)11-year-old boy_____(a/an)13-year-old boy she is ------- baby and she is very lovely.a:a-month-old b:an 8-months-old c:an 8-month-old d:a 8-months-old he is an 8 years old boy 为什么不对 He is an 8-year-old boy.对 8-year-old画线提问 This is an 8-year-old boy.That girl is 7 years old . an 8 years old boy an 8 years old boyan 8-year-old boy 哪句对?我对第一种结构混淆了 可以做定语吗? 中间有—和没—怎么样啊?an 8 year old boy 和an 8 —year— old boy 改错1.I met an old friend sometimes last month 是a one-year-old boy还是an one-year-old boy a 11-year-old boy还是an 11-year-old boy 21.Yesterday ____ 8-year-old boy fell into the river.The boy was saved by___policemanA the/a B a/an C a/the D an/a the little boy with nothing on is just two month old翻译 请问是an eleven-year-old boy还是an eleven-year old a one-year-old boy为什么不是an Tommy is an one -year -old boy.哪错了 Maomao is an eleven-year old boy.的意思