③by表示外部的，尤其是暴力的或无意中造成某种结果的原因。例如：
Her body was bent by age.岁月使得他的腰也弯了。
The general died by his own hand.将军自杀了。
She took your umbrella by mistake.她错拿了你的雨伞。
④at表示某种情绪或动作的起因，多与“喜，怒，哀，乐”等义的词连用，常译作“听到……”，“看到……”。例如：
The whole nation was in deep sorrow at the news.听到这个消息，全国人民极为悲痛。
He jumped at the news.听到这个消息，他蹦了起来。
