单项选择题
A．We may forget what we have thought about. B．Our thoughts may be disturbed. C．Our mind may be harmed. D．We may have difficulty in finding the right words.
A．Because the world is becoming increasingly noisy. B．Because they have learned that noise is also is also a kind of pollution. C．Because noise is an unwanted waste for human beings. D．Because people knew little about noise befor
A．our society is becoming much worse than before B．in our modern society it is hard to lead a quiet life C．the old days were much happier than the present time D．it is impossible for us to reduce noise back to previous levels