Speaking is like Sparring because you apply different techniques based on attacks and defences and you don't know what will come next, just like speaking your conversation is based on questions and answers. If you give the wrong answers or questions, you might upset or hurt the other person. You should know when to stop in speaking same in sparring, if you don't know what techniques to apply you might hurt yourself or others, without control in speaking or sparring both will get hurt in the end!
