Learners can feel very ...... if an exercise is too difficult. 

People are destroying the air by adding ...... to it. 

The health of our children is being ...... by exhaust fumes. 

People in this region cultivate mainly rice and vegetables. 

The waste from the chemical factory is extremely ....... 

If people stop destroying animal's natural habitat, more species will survive and produce ....... 

Oil spills are having a devastating effect on coral reefs in the ocean. 

It is possible for local wildlife to coexist ...... industry.

What exactly is the influence of air pollution ...... human beings? 

The society was set up to ...... endangered species from extinction. 

The campaign will hopefully ensure the survival ...... the tiger.

Among the problems facing the national park's manager, the most serious ones are those of ...... and expansion. 

The panda's ...... habitat is the bamboo forest.

The factory was fined for ...... chemicals into the river. 

The ...... friendly products are designed not to harm the natural environment.