题干

广西龙江河镉超标,严重威胁着民众的饮水安全.为处理镉污染,当地政府组织人员在镉超标水域投放了大量烧碱或熟石灰,以及氯化铝,絮凝沉降镉离子,避免被人体吸收.则下列说法错误的是(  )


A:镉是人体必需补充的微量元素

B:此事件已对环境造成污染

C:熟石灰是氢氧化钙的俗称

D:烧碱和熟石灰都是碱

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A

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    Summer Science Class registration begins on March 8 ! If you are interested in science,the environment,or conservation and you are in grades 7 -12 ,sign up soon for Black Rock Forest Consortium's Summer Science Class program. You can download the Summer Science Classes 2013 brochure here. It is easy to register;just call 845-534-4517 or click here.

    Twelve-week-long courses in the natural sciences and the arts are offered at Black Rock Forest in Cornwall from July 15 through August 9.Two more classes are offered with site partners,including “The Art of Scientific Observation,” hosted jointly by Black Rock Forest Consortium and Storm King Art Center ,one of the world's leading sculpture parks ,and “A Nautical   Expedition” hosted jointly by the Consortium and the Constitution Marsh Audubon Center.

    We are delighted to announce two special “away” classes that are part of the Summer Science Class program this year: an“Adirondack Eco-Adventure” beginning August 11,and “Conservation Biology in Florida,” beginning June 23 and featuring field work on the Gulf Coast in cooperation with the University of Florida's Seahorse Key Marine Biological Laboratory. For more information on the Summer Science Class program,please read our press release. Black Rock Forest Consortium is a nonprofit organization founded in 1989 to advance scientific understanding of the natural world through research,education and conservation programs.