分析了铅芯作用良好的原因，并通过试验得出了以铅代钨的具体方案。
The reasons of fine performance of the lead core is analyzed, anda practicable plan of substituting tungsten for lead is found through tests.
在20世纪六、七十年代，每年都有数百名美国儿童因严重的铅中毒入院治疗，都与接触含铅涂料和汽油有关。
During the 1960s and early 1970s, hundreds of American children were hospitalized each year with severe lead poisoning linked to exposure from lead in paint and gasoline.
“有了这些严格的标准，美国的新一代人将会减少受铅排放的毒害，”他补充说。
"With these stronger standards a new generation of Americans are being protected from harmful lead emissions," he added.
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