a seven-years child与a seven-year child哪个对?大耳朵英语网说前面的对?为什么?

a seven-years child与a seven-year child哪个对?大耳朵英语网说前面的对?为什么? a seven-years child 有类似的用法吗 " a five-year plan. 一个五年计划"的YEAR不用加S,而 a seven-years child里的 I___（am,was）a child seven years ago. I___（am,was）a child seven years ago.急 The book is( ) for a seven-year-old child to read 选择词This book is () for a seven-year-old child to read 英语年龄的表达我知道She is seven years old 和She is a seven-year-old gi 对for seven years提问 用英语说一个四岁的孩子a four years' old child对吗? ( ) His danghter is ________.A seven years B seven year old an eight-year-old child与an eight years old child 的区别