题目内容:
Itcanbeinferredfromthelastparagraphthatscientists( ).
A.arepuzzledbythemysteryofforestpollution B.feelrelievedbytheuseofunleadedgasoline
C.stillconsiderleadpollutionaproblem
D.lacksufficientmeanstocombatleadpollution
参考答案:
答案解析: