cause alternative doubt benefit participant pollution
1. Wind energy is a/an ____________ source of energy.
2. The __________ of this fruit is it can prevent cancer.
3. I have no ____________ about her ability. She can do everything.
4. I am not a speaker. I am only the _________________.
5. Big cities have a lot of _____________ problems.
6. Smoking can ____cause_________ many health problems.