useless trivia: What Word Means: The Normal State Of Partial Contraction Of A Muscle?

Questions

In 1947 Tennessee ---------- play "A Streetcar Named Desire", opens. ?

In 1948 Ozzy ---------- heavy metal musician, born. ?

In 1952 Mel ---------- author/comedian, born. ?

In 1967 1st human heart transplant performed (Dr Christian---------- , S Africa). ?

In 1973 Pioneer 10 passes ---------- (1st fly-by of an outer planet). ?