If you don't pickup the correct SGML declaration when validating your XML, you will probably receive a lot of error messages.
如果在验证XML时，没有应用正确的SGML声明，则可能收到一些错误消息。
2
These two mechanisms, coupled with lots of trial and error, is how we can pickup pencil differently than a stapler, and now robots are starting to learn the same way.