The government has cracked down hard on those campaigning for greater democracy. [VERB PREP. + on]

政府严厉镇压了那些发起运动争取更广泛民主的人士。

There has been a lot of drinking. We are cracking down now. Anyone who gets caught is fired. [VERB PREP.]

最近有很多人喝酒。我们现在要开始严惩。抓住一个解雇一个。