Choose the correct answer.  

The less smoke is released into the air, the _______ the atmosphere becomes.

Choose the correct answer.  

Many endangered species will keep losing their _______ unless we reduce deforestation.

Choose the correct answer.  

Nuclear, wind, and solar power are _______ energy sources.

Choose the correct answer.  

The huge crowd is _______ about the local water pollution, showing lots of signs and banners on the streets.

Choose the correct answer.  

In this zoo, some scientists are trying to _______ some species that are seriously endangered.

Choose the correct answer.  

If factories _______ proper filters, they wouldn’t have released so many harmful gases into the air.

Choose the correct answer.  

Using _______ products which are not harmful to the environment is now becoming more and more popular.

Choose the correct answer.  

Some species might go extinct _______ we reduce deforestation.