Some improvement suggestions for newbie reading the client tutorials (section 5 to 8)

https://www.apollographql.com/docs/tutorial/client.html#react-apollo
- no react and react-dom imports
- where did Pages component came from?

https://www.apollographql.com/docs/tutorial/queries.html#fragments
- LAUNCH_TILE_DATA should be above GET_LAUNCHES
- please mention src/pages/launch.js

https://www.apollographql.com/docs/tutorial/mutations.html#authenticate
- where did resolver and typeDefs came from?

https://www.apollographql.com/docs/tutorial/local-state.html#local-query
- where did injectStyles() came from?

https://www.apollographql.com/docs/tutorial/local-state.html#virtual-fields
- where did GET_CART_ITEMS came from?

https://www.apollographql.com/docs/tutorial/local-state.html#direct-writes
- where did StyledButton component came from?

检查链接的客户端教程中关于 React Apollo、片段、身份验证、本地查询、虚拟字段和直接写入的部分。根据教程上下文检查列出的每个缺失的导入、组件、常量、解析器、typeDefs 或源文件引用；完成的标准是每个被引用的项目都已介绍，或其位置已得到说明。

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