The rivers and canals are dry because there are many dams in the upstream. => Due to the presence of many dams in the upstream, the rivers and canals are dry.

The ocean water became contaminated by liquid petroleum as a result of the oil spills. => Because of the oil spills, the ocean water became contaminated by liquid petroleum.

Unless treated waste water is used and managed properly, health effects will occur. => If treated waste water is not used and managed properly, health effects will occur.

People continue using plastic, there will be more plastic than fish in the ocean. => Unless people stop using plastic, there will be more plastic than fish in the ocean.

The reason why endangered species become extinct is that humans are careless and lack of knowledge. => Since humans are careless and lack knowledge, endangered species become extinct.

We can’t slow down climate change unless we stop using fossil fuels. => If we don’t stop using fossil fuels, we can’t slow down climate change.

Let’s encourage our friends to use reusable bags instead of plastic ones. => Why don’t we encourage our friends to use reusable bags instead of plastic ones?

It’s a good idea for the governments to punish the polluters with large fines. => The governments should punish the polluters with large fines.

If global warming continues, the ice caps will melt. => If global warming continues, the ice caps will melt.