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- allowable background level 容许本底水平
- Radioactive elements are at the normal background level, causing no deleterious pollution. 环境辐射在正常范围之内，不存在任何人为造成的放射性污染。
- Radioactive elements are at the normal background level,causing no deleterious pollution. 环境辐射在正常范围之内，不存在任何人为造成的放射性污染。
- The distance at which the magnetic field from the line becomes indistinguishable from typical background levels differs for different types of lines. 要使输电线产生的电磁场辐射等级和典型的背景电磁辐射等级差不多，这个距离得随输电线的不同而变化。
- A Study on the Selenium Background Level in the Soils in Guizhou 贵州省土壤硒的背景值研究
- He has a strong political background. 他有强大的政治背景。
- The road is too narrow to allow the passage of gondola. 这条街太窄，大型货车不能通过。
- That incessant background music gets on my nerves. 那没完没了的背景音乐令我非常烦恼！
- He has a working-class background. 他是工人阶级出身。
- Please open a window to allow the air to circulate. 打开窗子让空气流通。
- Get the fall in the background, will you? 把瀑布拍进背景中去好吗？
- It is too dark outside to allow of walking. 外面太黑了，不能出去散步。
- A background accompaniment, as for a performer. 伴奏为一个演奏者配音伴奏
- My boss doesn't allow me to use the telephone. 老板不许我使用电话。
- Allow three clear days for the letter to arrive. 信要整整三天才能到达。
- We will not allow ourselves to be trampled upon. 我们决不容许自己被人轻视。
- She came from a privileged background. 她出身於特权阶层。
- A round the world ticket allow several stopover. 环球飞机票可允许乘客在途经的几地方稍做逗留。
- He came from an impoverished background. 他出身贫寒。
- This book gives the background of the Civil War. 这本书叙述了南北战争的背景。
