1. risk: to get into a situation where something very unpleasant might happen to you as a result of something you do

例：

Many refugees risk death or arrest in their attempts to flee persecution. （很多难民为了不被迫害而冒着死亡或被捕的危险逃离自己的国家。）

risk your life

The Carnegie Hero awards are given to those who risk their lives to save others. （卡内基英雄奖是颁给那些舍己救人的勇士的。）

I'm not going to risk my neck (= risk my life) just to save a common criminal. （我不会冒着生命危险去救一个普通罪犯。） 

Why risk life and limb (= risk your life and health) jumping out of a plane just to raise money 

for charity?（为什么要为了慈善筹款冒着生命危险从飞机上跳出去？）

2. run a risk: to be in a situation where something bad might happen to you, especially because of something you do

例：

The people who use these drugs are often unaware of the risks they are running. （使用这些药的人往往不知道存在的风险。）

run a risk of doing something

Men run a greater risk of dying from heart disease than women. （男性死于心脏病的风险高于女性。）

Rather than running the risks of using harmful pesticides in your garden, try using natural or organic methods of pest control. （与其在自家花园里使用杀虫剂，带来对环境的危害，还不如试试纯天然或有机的除虫方法。）

Anyone traveling without a passport runs the risk of being arrested. （在外国旅行时没有护照可能会被抓。）

3. be at risk: to be in a situation in which you risk being harmed or losing something very important or valuable

例：

The children were removed from the family because their father was violent and they were believed to be at risk. （因为孩子们的父亲滥用暴力，社署认为孩子们在家里有危险，所以把他们接走。）

We must stop these rumors; the firm's reputation is at risk. （我们要阻止流言继续传播，公司声誉岌岌可危了。）

Accidents in the home are extremely common, and elderly people are most at risk. （老年人最有可能在家中发生事故。）

That would mean putting other children at risk . （那意味着将其他孩子置于危险的境地。）

at risk from

Women are more at risk from the harmful effects of alcohol than men. （女性比男性更容易受到酒精的危害。）

The future of the party is clearly at risk from internal divisions. （这个政党将来很可能会内讧。）

at risk of

Those with fair skin are more at risk of skin cancers than those with dark skin. （肤色浅的人比肤色深的人更容易得皮肤癌。）

Wildlife along the coastline is at risk of serious pollution from the tankers. （油船带来严重污染，沿海生物都有可能会深受其害。）

Their children are also at high risk of developing the disease. （他们的孩子得这个病的可能性也很高。）

The hospital refused to move her, implying she was still at risk of committing suicide. （院方指出她仍存在自杀倾向，不让她转院，）

Unless funding becomes available, the entire project is at risk. （除非资金到位，否则整个工程有停工的危险。）