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Did Steve Young play any notable games while a backup?
Substituting for an injured Montana, early in the first quarter of a 1987 game against the Chicago Bears, he threw four touchdown passes in a 41-0.
Did they win that game?
41-0 victory.
Did he play any other notable games?
he replaced Montana in the second half after the team fell behind 27-10.
The 49ers still lost the game, but Young had a fairly good performance.
Who were the 49ers playing in this game?
Minnesota Vikings.
When was this game being played?
1987.
Was this game played at the 49ers' stadium or the Vikings' stadium?
CANNOTANSWER.

Question: Did the 49ers play well during the 1987 to 1990 period?
Self-contained rewrite: Did the 49ers play well during the 1987 to 1990 period?