重点讲解：
1. be discharged from 允许…离开(医院、军队)；
When he was discharged from the hospital, he had lost 20 pounds.
出院的时候，他的体重减轻了20磅。
2. attribute to 把…归因于；把…归咎于；
The coach attributed the team's victory to training and practice.
教练把球队的胜利归功于平时的训练。
3. set off 动身；出发；启程；
We set off in a southerly direction.
我们向南出发了。
4. ahead of 早于；在…之前；
And its monetary-policy arm's overstimulative policy ahead of the credit boom arguably made it a stoker of systemic risk.
而美联储货币政策部门在信贷极度扩张之前实施的过度刺激经济的政策对系统性风险起到了推波助澜的作用。