26. We should end a letter
27. If we keep on
28. Many factories still allow
29. People must learn about keeping the environment
30. We are worried that rivers and canals are becoming more and more
31. We are talking about the
32. Environmental groups want a total
poison)
with the words "Sincerely yours" (polite)
the air, more people will suffer from respiratory diseases (poll
such as toxic waste, to flow into our river (pollute)
(pollute)
of natural resources (preserve)
(pollut
on the dumping of nuclear waste (prohibit)