black market 黑市（交易）；在黑市卖；做黑市交易；非法商品冒充合法商品

【例句】
One of his kidneys had been removed, apparently by a gang selling human organs on the black market.
显然，这是一起由黑帮分子操纵，通过下药迷倒普通人并割取其器官进行黑市交易的恶性案件。

He has no imagination. I can unload plenty of cotton in the black market if he'll make a deal.
他这个人没有想象力，要是他愿意和我做一笔交易，我有办法在黑市上抛售掉许多棉花。