useless trivia: What Word Means: Arctium - The Root Of The Great Bur - A Kind Of Clover?

Questions

In 1977 Egyptian President Anwar Sadat became first ---------- leader to address Israel's Knesset. ?

In 1980 Steve Ptacek in Solar Challenger makes first solar-powered---------- . ?

In 1986 UN's WHO announces first global effort to combat---------- . ?

In 1959 Jack Benny (Violin) and Richard ---------- (Piano) play their famed duet. ?

In 1980 The "Who Shot JR" episode of "---------- " begins the tradition of season-ending cliff-hangers. ?