1. If/ we/ destroy/ the ozone layer/ what/ save/ us/ the UV rays?

⇒If we destroyed the ozone layer what would save us from the UV rays

2. If/ people/ not really care/ the environment/ they/ not try/ save it.

⇒If people didn't really care about the environment,they wouldn't try to save it

3. The river/ not be/ so polluted/ if/ factories/ not dump/ waste/ it.

⇒The river would not be so polluted if factories didn't dump waste to it

4. We/ be/ less worried/ if/ oil spills/ not have/ such destructive effects

⇒We would be less worried if oil spills didn't have such destructive effects

=>

1. If we destroyed the ozone layer, what would save us from the UV rays?

2. If people didn't really care about the environment, they wouldn't try to save it.

3. The river wouldn't be so polluted if factories didn't dump waste into it.

4. We would be less worried if oil spills didn't have such destructive effects.

Câu đk loại 2 : If S V2/ed, S would V.