background level

常见例句

The new safety level is about 100 times higher than the background level of dust at ground level.
新的安全水平比地平面灰尘背景水平高出一百倍，也比从火山爆发以来测试飞机在英国上空所测的数据要高很多。
The U.S. Nuclear Regulatory Commission recommends that beyond this background level, the public limit their exposure to less than an additional one millisievert per year.
美国核管理委员会建议，在此背景辐射水平之上，公众每年可多承受不超过1毫希的辐射。
blog.sina.com.cn
The new safety level is about 100 times higher than the background level of dust at ground level.
新安全标准约是地水准平面尘埃本底水准的100倍，也比自火山喷发后在英国领空作科学研究的飞机所得的数据高很多；

Critics say the national exam is biased, since it presumes a level of knowledge and cultural background that students from working class families may not have.

The new safety level is about 100 times higher than the background level of dust at ground level.
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The background level of tropospheric ozone is inexorably rising as volatile organic compounds are released from burning coal and oil.
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Indeed, Warner Marzocchi and Anna Maria Lombardi of the INGV showed that a few hours before the earthquake actually struck modelling would have suggested the chance that a powerful quake would occur within 10 kilometres of L'Aquila within three days rose from one in 200, 000 (the background level) to about one in 1, 000.
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