市长承诺严厉打击故意破坏公物行为。

The mayor promised to crack down on ___vandalism.

例如，故意破坏行为在青少年中非常普遍。

___Vandalism, for example, is very common among teenagers.

故意破坏行为源于缺乏其他合适的活动。

___Vandalism stems from the lack of any other suitable activities.