If something necessitates an event, action, or situation, it makes it necessary.
例句
A prolonged drought had necessitated the introduction of water rationing...由于持续干旱,用水需要实行配给了。Frank was carrying out fuel-system tests which necessitated turning the booster pumps off.弗兰克在做燃料系统测试,这一测试需要关掉升压泵。