Iii. grammar 1. fill in the sentences with the correct forms of the verbs (active or passive) 1). when we (pollute) the air, the climate (change). 2). nature (damage) when people (throw) away plastic bottles. 3). animals (hurt) when we (leave) litter in the forest. 4). when trees (break), birds (disturb). 5). when litter (throw) in the river, water pollution (cause)