句柄不支持异步操作。可能需要更改 FileStream 构造函数的参数，以指示此句柄是以同步方式打开的(即不是为重叠 I/O 打开)。

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