In Czech, you use double negatives, triple negatives, even quadruple negatives. I still can’t get my head around the phrase I heard someone – ‘nikdo nikdy nic nevidel .’ Crazy!
In English, you cannot do this, and as a rule, avoid double negatives. Instead of saying, „I don’t know nobody who works in America,“ you need to say, „I don’t know anybody who works in America.“
In this way, Brits often use the negative to express things. Instead of saying, „I know nothing,“, we’d much more commonly say, „I don’t know anything.“
The only times we use double negatives is to express something for a very particular reason. For example, you might say, „I didn’t say I don’t like him“, meaning I haven’t actually said that I don’t like him (though it’s probably true). The opposite – „I said I like him“ – is definitely not what you want to say. So, we employ this double negative tactic to express ourselves.