事故发生后，警方封锁了街道。

The police ___closed ___off the street after the accident.

几条道路因马拉松赛而被封闭。

Several roads were ___closed ___off for the marathon.

为确保安全，他们用路障封锁了建筑工地。

To ensure safety, they ___closed ___off the construction site with barriers.