Did Robin William really ad lib all those great Mork lines?

Thank God it’s Friday (Question Day). What’s yours?

Nick gets us started:


Is there much room for ad libbing on the set of sitcoms? I know in films it can work because you shoot multiple takes - but in a sitcom format (i'm thinking of Robin Williams in Mork and Mindy) do writers appreciate when actors ad lib or is it generally frowned upon?

Some shows like CURB YOUR ENTHUSIASM are built