There is a ban on smoking in petrol stations.

加油站禁。

"Petrol is highly combustible, so smoking is strictly forbidden during the handling of it."

"汽油极易燃烧,处理时严格禁。"

As of now, smoking is forbidden in this house.

从现在起，这栋房子里禁。

You know full well that smoking is forbidden in this room.

你很清楚这房间里禁。

The doctor forbids him to smoke.

医生禁他。

No smoking allowed.; Smoking not allowed.

禁。

No Smoking signs.

禁的标志。

No smoking in the auditorium.

礼堂内禁。