1、They will knock back 6.1 million litres of beer, roughly equivalent to one litre per person.
他們將會喝掉610萬升啤酒，約合每人一升。

2、How much can you knock back at a time
你一次能喝多少

3、He certainly knows how to knock back the whisky!
他肯定知道怎樣把這些威士忌酒一口喝下去！