英语语法分析

When people engage in activities that help others, their brain releases endorphins, the brain's natural opiates, which induce in people a feeling of well-being.

当人们参与有助于他人的活动时，他们的大脑会释放出内啡肽，这是一种大脑中天然的麻醉剂，能让人产生幸福感。

He was a quack dentist on his rounds, who was offering to the public full sets of teeth, opiates, powders and elixirs.

那人是一个兜卖整套牙齿、牙膏、牙粉和药酒的走江湖的牙科医生。

This finding supports the theory that placebos reduce pain by encouraging the brain to produce more natural opiates than usual.

这一发现支持了该理论：安慰剂是通过促使大脑产生比通常更多的天然麻醉剂来减少疼痛的。