eight years old与eight- year-old
问题描述：
eight years old与eight- year-old
答
eight years old用做表语或状语,表示8岁大了.
eight- year-old是形容词,用做定语,表示8岁大的...
例如：She is eight years old.(表语）
She is a beautifull girl,eight years old.(状语）
She is an eight-year-old girl.(定语）