what is desf and dumb,but can always tell the truth?

what is desf and dumb,but can always tell the truth? what can't talk but always speak the truth?意思 What can‘t walk,but can speak the truth? tell the truth,the the whole turth and nothing but truth. But the truth is we can't stay there for a lifetime,what we what is the boy and girl can you tell me what cah't talk but can speak the truth? Where can you never tell the truth? where can you never tell the truth he made an oath that he would tell the truth and nothing but Can you tell me what is the relation between you and the own no one ___is here.please tell me the truth,and then i can he