This, however, may push others towards the black market or offshore, further undermining the credibility of the official exchange rate.

然而这会使其它人走向黑市或海外市场，这样就会更加削弱官方汇率的可信度。

youdao

In Zimbabwe, the black-market exchange rate is nearly ten times the official one.

ECONOMIST: Zimbabwe

Now, dollars sell on the black market at three times the official exchange rate and Maduro has had to devalue Venezuela's currency, the bolivar, twice this year.

NPR: Tensions Up In Venezuela After Polls Close

Venezuela Keeps Official Exchange Rate Despite Flourishing Currency Black Market Trade.

CENTERFORSECURITYPOLICY: Venezuela Brief: Countdown to Tyranny I