STream class 的哪些子class 支持在 C# 中查找（不在文档 ffs 中）
Which subclasses of the STream class support seeking in C# (not in the docs ffs)
一般来说，我只想知道C#中哪些流支持查找。查了文档，微软的大神们解释了概念，但实际上并没有说可以求哪些。
如the docs所述：
Streams can support seeking. Seeking refers to querying and modifying the current position within a stream. Seek capability depends on the kind of backing store a stream has. For example, network streams have no unified concept of a current position, and therefore typically do not support seeking.
能搜的不能一一列举，要看流量背后有什么后盾。
如果您想知道流是否可以搜索，请检查 CanSeek-Property. If it's true, you can use the seeking properties and methods available. Again, see the docs (remarks section)。
If a class derived from Stream does not support seeking, calls to Length, SetLength, Position, and Seek throw a NotSupportedException.
一般来说，我只想知道C#中哪些流支持查找。查了文档，微软的大神们解释了概念，但实际上并没有说可以求哪些。
如the docs所述：
Streams can support seeking. Seeking refers to querying and modifying the current position within a stream. Seek capability depends on the kind of backing store a stream has. For example, network streams have no unified concept of a current position, and therefore typically do not support seeking.
能搜的不能一一列举，要看流量背后有什么后盾。
如果您想知道流是否可以搜索，请检查 CanSeek-Property. If it's true, you can use the seeking properties and methods available. Again, see the docs (remarks section)。
If a class derived from Stream does not support seeking, calls to Length, SetLength, Position, and Seek throw a NotSupportedException.