Not only are sweeteners much cheaper ingredients than sugar, they have also been one of the central mechanisms by which the food industry persuades us to buy and consume more.

甜味剂不仅比糖便宜得多，也是食品工业说服我们购买和消费更多（食品）的核心机制之一。

He improved on what came before by making his gun's central mechanism, or receiver, out of aluminium rather than heavy steel and its stock out of fibreglass.

他对之前的技术进行了改进，用铝而不是重钢制造了枪的中央机构或机匣，并用玻璃纤维制造了枪托。