A number of them release dangerous organic compounds which are unsafe for both human beings and the natural（ ）.
A.正确答案Cmaterial
B.cycle
C.resources
D.setting
A number of them release dangerous organic compounds which are unsafe for both human beings and the natural（ ）.
A number of them release dangerous organic compounds which are unsafe for both human beings and the natural（ ）.
A.正确答案Cmaterial
B.cycle
C.resources
D.setting
