These methods prevent pregnancy. [VERB noun]

这些方法能防止怀孕。

Further treatment will prevent cancer from developing. [VERB noun + from]

进一步的治疗将阻止癌症恶化。

We recognized the possibility and took steps to prevent it happening. [VERB noun verb-ing]

我们认识到了这种可能性，并且采取了一些预防措施。

He said this would prevent companies from creating new jobs. [VERB noun + from]

他说这将使公司无法创造新的工作机会。

Its nationals may be prevented from leaving the country. [V n from -ing]

其国民可能会被禁止出境。

The police have been trying to prevent them carrying weapons. [VERB noun verb-ing]

警方一直都设法阻止他们携带武器。