美国科学家发现,为树木注射抗污染化学剂—二脲乙烯(ethylenediurea),可以把臭氧污染对树叶的危害程度减少94%。臭氧是一种主要的空气污染物。它不仅会毁坏庄稼,还会使树木的叶子变黄、枯萎并脱落。臭氧还会使茂盛的树木变衰弱,停止生 American scientists found that injecting trees with an anti-pollution chemical, ethylenediurea, can reduce the harmful effects of ozone pollution on the leaves by 94%. Ozone is a major air pollutant. Not only does it destroy crops, it also turns the leaves of the trees yellow, wilt and fall off. Ozone can also make lush trees weak, stop students