Ex4.Write the verbs in brackets in the passive voice.
ACID RAIN
Acid rain 1) was discovered (discover) by a Scottish scientist in the 1850s, and since the 1960s a lot of research 2)……. (done) about it. It 3)…….. (mainly cause) by factory smog and car fumes. At every moment these chemicals 4)……. (release) into the air. There, they mix with water and 5) ……. (store) in clouds until it rains. Recently, many famous buildings and statues 6)…… (damage) by acid rain and in the future scientists predict that huge areas of forestland 7) …….. (destroy) by acid rain. Acid rain can 8)…… (reduce) if we burn fewer fossil fuels, but we need to act now!