Error at file http://www.w3.org/TR/voicexml20/vxml-synthesis-restriction.xsd, li
ne 30, char 53
  Message: Could not find a declaration in the schema to be redefined correspond
ing to 'say-as'

Error at file http://www.w3.org/TR/voicexml20/vxml-synthesis-restriction.xsd, li
ne 43, char 52
  Message: Could not find a declaration in the schema to be redefined correspond
ing to 'audio'

Fatal Error at file , line 0, char 0
  Message: An exception occurred! Type:NetAccessorException, Message:Could not c
onnect to the socket for URL 'http://www.w3.org/TR/voicexml20/synthesis-core.xsd
'

Fatal Error at file http://www.w3.org/TR/voicexml20/vxml-synthesis-restriction.x
sd, line 25, char 55
  Message: Fatal error encountered during schema scan
这是那个xml，这个文件那里有错呢

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://www.w3.org/2001/vxml
               http://www.w3.org/TR/voicexml20/vxml.xsd"
                version="2.0">
        <form>
         <field name="drink">
           <prompt>Would you like coffee, tea, milk, or nothing?</prompt>
           <grammar src="drink.grxml" type="application/srgs+xml"/>
         <block>
           <submit next="http://www.drink.example.com/drink2.asp"/>
         </block>
         </field>
        </form>
</vxml>