Question: National Lampoon's Christmas Vacation is a film that stars an actor known for playing Dr. Leonard Hofstadter in what CBS sitcom?
Sentence (from "Johnny Galecki"): He is known for playing David Healy in the ABC sitcom "Roseanne" from 1992 to 1997 and Dr. Leonard Hofstadter in the CBS sitcom "The Big Bang Theory" since 2007.
Relevant evidence: Yes