根据搜索结果，三年级英语上册第一单元的句子主要包括以下内容（综合多个版本教材）：

一、日常问候类

1. Hello/Hi + 名字

- Hello, Tom! / Hi, Lily!

2. Good morning/afternoon

- Good morning, teacher! / Good afternoon, everyone!

3. Goodbye/Bye

- Goodbye, Mike! / Bye, Zhang Peng!

二、自我介绍类

4. I'm + 名字

- I'm Amy. / I'm Gao Wei.

5. This is + 名字

- This is my friend, John. / This is my new friend, Zhang Peng.

6. How old are you？

- I'm eight years old. / I'm 9 years old.

三、基础问答类

7. Where are you from？

- I'm from China. / I'm from New York.

8. What's your name？

- My name's Peter. / My name's Li Yan.

9. Nice to meet you.

- Nice to meet you! / Nice to meet you too.

四、日常活动类

10. What's this in English？

- It's a book. / It's a pencil.

11. Can you spell it？

- B-O-O-K. / C-A-T-E.

12. Let's + 动词原形

- Let's make some cards. / Let's play a game.

五、情景对话类

13. May I...？

- May I come in？ / May I have some water？

14. Please + 动词原形

- Please sit down. / Please close the door.

15. I have to...

- I have to go now. / I have to finish my homework.

这些句子覆盖了三年级英语上册第一单元的核心语法和常用表达，建议结合教材配套练习巩固学习。