If you *heat* (heat) ice, it melts.

When you *mix* (mix) red and blue, you get purple.

If dogs *are* (be) hungry, they bark.

Plants *die* (die) if they don’t get enough water.

If you *cut* (cut) onions, you often cry.

Iron *rusts* (rust) when it is exposed to moisture.

If you *drop* (drop) an apple, it falls to the ground.

People generally *yawn* (yawn) when they are tired.

Water *boils* (boil) if you heat it to 100°C.

If it *rains* (rain), plants grow.

Cars *stop* (stop) when they reach a red light.

If you *touch* (touch) a fire, it burns.

Food *spoils* (spoil) if it is not refrigerated.

If the sun *sets* (set), it gets dark.

Bread *rises* (rise) if you add yeast.

Exercício 2 – Complete as frases com a condição zero, seguindo o exemplo dado.

If you *press* (press) that button, the machine turns on.

Cats *flee* (flee) if they feel threatened.

If it *snows* (snow), the roads get slippery.

Babies usually *cry* (cry) when they are hungry.

Food *doesn’t taste* (not taste) good if it is overcooked.

If you *water* (water) a plant regularly, it thrives.

When you *freeze* (freeze) water, it turns into ice.

If you *expose* (expose) film to light, it gets ruined.

You *find* (find) fog in regions where warm air meets cold air.

If you *apply* (apply) pressure to a liquid, it become a solid.

Sugar *dissolves* (dissolve) if you stir it into hot water.

If we *pollute* (pollute) the environment, we destroy habitats.

Ice *does not melt* (not melt) if the temperature is below 0°C.

When you *push* (push) a swing, it moves back and forth.

If you *combine* (combine) hydrogen and oxygen, you get water.