at which point的用法
at which point用于引导定语从句，其意为“就在这时”“就在那时”等，在许多情况下相当于 and at that (this) moment。如：
He lost his temper, at which point I decided to go home. 他发脾气了，这时我就决定回家了。
The speaker paused to examine his notes, at which point a loud crash was heard. 讲演者停下来查阅他的笔记，就在这时，听到了砰的一声巨响。
The film started to get very violent, at which point I left. 那部电影看着看着出现了极残暴的场面，我立刻就走了。
【注意】千万不能在 at which point 前加并列连词。如：
讲演者停下来查阅他的笔记，就在这时，听到了砰的一声巨响。
误：The speaker paused to examine his notes, and at which point a loud crash was heard.
正：The speaker paused to examine his notes, at which point a loud crash was heard.
正：The speaker paused to examine his notes, and at that moment a loud crash was heard.
。