1．occur vi. 发生；出现 The accident occurred at five o'clock. 事故发生在5点钟。 知识拓展 occur to 被想到；被想起 [译]他突然想起他没有锁门。 [误]He suddenly occurred that he hadn't locked the door. [正]It suddenly occurred to him that he hadn't locked the door. 注意：因为occur意为“come to one's mind”，所以occur的主语通常为某事，只是为了保持句子的平衡，而将该主语用it来表示，后置的that­clause是真正的主语。