We must/mustn't light campfires in the forest.
We mustn't light campfires in the forest.
We must/mustn't plant more trees.
We must plant more trees.
We must/mustn't waste water while we are washing the dishes.
We mustn't waste water while we are washing the dishes.
We must/mustn't cut down trees.
We mustn't cut down trees.
We must/mustn't use eco-friendly products.
We must use eco-friendly products.
We must/mustn't turn off the lights when we sleep.
We must turn off the lights when we sleep.
We must/mustn't stop deforestation.
We must stop deforestation.
We must/mustn't recycle paper and bottles.
We must recycle paper and bottles.
We must/mustn't use pesticides.
We mustn't use pesticides.
We must/mustn't pollute the air.
We mustn't pollute the air.