数字与计量单位的表达 — 英语情景题

Read and complete the dialogue.（补全对话，每空一词） Tom: Hi, Sam! How long does it take you to walk to school? Sam: It takes about twenty (1)________ (分钟). Tom: Twenty minutes? That's fast! How far is it? Sam: It's about one (2)________ (千米). Tom: Wow! And how long is one hour? Sam: One hour has (3)________ minutes.