そうになる

expression, godan verb (-ru)

almost happen; be about to happen

Attaches to the -masu stem of a verb to express that an action or event nearly occurred but did not. Often implies a narrow escape or a last-moment prevention.

• 転ころびそうになったが、手てすりにつかまって助たすかった。

  I almost fell, but I grabbed the handrail and was saved.

• 大だい事じな書しょ類るいを忘わすれそうになった。

  I almost forgot the important documents.