5 a: The snow falls. It covers the ground with a protective layer. (when)
When the snow falls, it covers the ground with a protective layer.
5 b: Her cubs are born. The lioness licks them all over. (as soon as)
As soon as her cubs are born, the lioness licks them all over.
5 c: The paper is collected. It is sent for recycling. (once)
Once the paper is collected, it is sent for recycling.
5 d: Volcanoes erupt. They send huge amounts of smoke into the air. (before)
Before volcanoes erupt, they send huge amounts of smoke into the air.
5 e: The plants perspire. The air becomes humid. (when)
When the plants perspire, the air becomes humid.
5 f: The trees are cut down. The forest is gradually destroyed. (and)
The trees are cut down and the forest is gradually destroyed.
