先总结一下，改天继续写
- Indexed Members and Element Initializers
- Auto-Properties with Initializers
- Primary Constructors
- Static Using Statements
- Declaration Expressions
- Exception-Handling Improvements
- Additional Numeric Literal Formats
- Null-Conditional Operator
- Nameof Expressions
- Expression Bodied Functions and Properties
- Event initializers
- NameOf operator
感觉没有太大的新功能，都只是让开发更容易和方便