lpBuffers
A pointer to an array of WSABUF structures. Each WSABUF structure contains a pointer to a buffer and the length, in bytes, of the buffer. This array must remain valid for the duration of the send operation.
如果用了 Overlapped 就得保持到发送结束,
如果没有用Overlapped ,则是阻塞模式,返回时就可以再修改