当然，以下是几个使用“how old”的例句：
询问年龄：
- How old are you? （你多大了？）
- I'm wondering how old your sister is. （我想知道你姐姐多大了。）
在对话中确认信息：
- The book says he was 30 when he wrote it. How old do you think he is now? （书上说他写这本书时是30岁。你觉得他现在多大了？）
- She looks so young, but how old is she really? （她看起来好年轻，但她到底多大了呢？）
表达惊讶或好奇：
- Can you believe he's only 25? I thought he was much older! How old did you think he was? （你能相信他才25岁吗？我以为他年纪大多了！你以为他多大了？）
- Look at that child; how old do you suppose she is? （看那个孩子，你猜她多大了？）
用于比较：
- My brother is two years older than me. How old am I if he's 28? （我哥哥比我大两岁。如果他28岁了，那我多大了？）
- How old were you when you started learning to drive, compared to your friends? （和你朋友相比，你开始学习开车时多大了？）
这些例句展示了“how old”在不同情境下的用法，包括直接询问年龄、在对话中确认信息、表达惊讶或好奇以及进行比较等。
