background level

基本解释

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麪灰塵背景水平高出一百倍，也比從火山爆發以來測試飛機在英國上空所測的數據要高很多。
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.
美國核琯理委員會建議，在此背景輻射水平之上，公衆每年可多承受不超過1毫希的輻射。
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The new safety level is about 100 times higher than the background level of dust at ground level.
新安全標準約是地水準平麪塵埃本底水準的100倍，也比自火山噴發後在英國領空作科學研究的飛機所得的數據高很多；

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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