How far is it from your home to school It's about 20 minutes' walk 这里为什么不用twenty-minute walk不是经常说a five-year-old boy
问题描述：
How far is it from your home to school It's about 20 minutes' walk 这里为什么不用twenty-minute walk
不是经常说a five-year-old boy
答
连字符“-”连接的形式不是什么情况都可以用的.在下列情况可以：如
a five-year-old boy / a three-legged table / a kind-hearted man
It's a twenty minutes' walk
而twenty minutes' 是名词所有格形式作定语