how to get each smarttag in smarttags in c++ com

[c.cai]

in the api reference , smarttags only has a count property . But i found we
can use VB to get each smarttag in the smarttags .

In c++ , i am using IDispatch to invoke functions in smarttags with the name
"Item" , "get_Item" , "get_item" . All failed .

How can i get the smarttag in the smarttags ?

Thanks.