X.
a. We cannot swim in this part of the river because the water is highly polluted.

b. The company does not produce recycled paper since it is more expensive to produce them regular paper.

c. We have "a green week" three times a year to make people aware of the problem of pollution.

d. No one wants to go swimming or sunbathing there as the area around the beach is full of trash.

e. We could not keep on cleaning the beach because it started to rain.

f. Mr. Minh is admired as he dedicates all his life to protecting the Environment.