Jawaban:

C. Expression : in my opinion

Clause : this fact is terrible

D. Expression : I believe

Clause : they don't realize the danger

Conjunction : because

Clause : they don't have sufficient about healthy living

E. Expression : I think

Clause : the government must make a regulation

Conjunction : that

Clause : prohinits people from building houses near trash disposal areas

F. Expression : I think

Clause : the efforts to keep our environment clean and tidy need hard work from both the citizens and the governments