Chia dạng đúng của từ trong ngoặc

19. Tsunami, tornado, drought, mudslide, earthquake are........................…………..….disasters. (NATURE)

20. Many people in this area have cholera because they drink _________water. (TREAT)

21. The....................................................... are concerned about the oil spills in East Sea. ( ENVIROMENT)

22. If we go on littering, the environment will become seriously…….............................…….. (POLLUTE)