17.The movie is to deucate people about environmental problems ______ our planet.
I smell something ____ ______ in the kitchen. Can I call you back in a minute?
.At the beginning of class, the noise of desks ____ could be heard outside the classroom.
_____and I’ll get the work finished.
.This washing machine is environmentally friendly because it uses _____water and electricity than _____models.
---Mom, what did your doctor say? ---He advised me to live _____the air is fresher.