1.block release （到高校进行一周或几周的）短期脱产进修
例句：We are short-staffed at the moment as two of our team are on block release.
我们目前人手不足，因为小组里有两人脱产学习。

2.black economy 黑市经济（指为逃税而隐瞒收入的地下经济）
例句：The part of an economy which is not declared to the tax authorities is known as the black economy.
不向税务部门申报的经济领域被称为黑市经济。

3.Black Friday （尤指经济领域内灾难性的）黑色星期五，灾难性的一天

4.Black Monday （股市狂跌的）黑色星期一

5.blue chip 蓝筹股、绩优股
例句：She put her money into blue chips.
她把钱投资在绩优股上。