句柄不支持同步操作。可能需要更改 FileStream 构造函数的参数，以指示此句柄是以异步方式打开的(即为重叠 I/O 显式地打开)。

Handle does not support synchronous operations. The parameters to the FileStream constructor may need to be changed to indicate that the handle was opened asynchronously (that is, it was opened explicitly for overlapped I/O).