根据四年级上册英语教学内容，关于"online"的造句可归纳如下：

一、核心造句模板

购物类

- We can shop online. Let’s take it.

- How much is it？ It is... yuan.

在线活动类

- I like chatting online.

- Both players are online.

数据库/工具类

- We plan to build an online database.

二、发音与语法重点

学生需掌握单词中"ts"、"ds"、"wh"、"wr"的发音规律，例如：shop online 。

三、拓展应用场景

网络服务类：Go to the website today and you can unsubscribe online.

企业应用类：The site acts as a portal for thousands of online dealers.