black out level

基本解释

Either way, I always wonder if there is such a huge demand for black market library cards that it justifies out level of concern? I hope so…
不管怎样，我始终怀疑是否真有黑市借书证这样一种巨大需求，以使对借书证的过度关注合理化？
Peaks in the Black Mountains range between 1, 500 m and 2, 700 m above sea level, and fast-flowing rivers have carved out deep gorges in the lower mountain areas.
黑山顶的山脉在海拔1500米到2700米之间，急流在较低的山区冲刷出很深的峡谷。
Theory: utilize the difference of liquor level to form vacuum to completely wash the black liquor out of pulp layer, a three-phase adverse current washing method is adopted.
原理：利用液位差，形成真空度把浆层里的黑液过滤完进行洗涤，我们是采用三段逆流洗涤的方法。
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