1. vi.发生，举行，存在　 happen; take place; exist
2. vi.被发现，想到〔起　〕 be found; come into one's mind

　～ free　自由存在
　～ natural　天然存在
　hardly ～　几乎不发生
　just ～　刚刚发生
　never ～　从没发生
　only ～　只存在
　～ first　首先想到
　～ distressingly　令人痛苦地发生
　～ frequently　屡次发生
　～ historically　历史性地发生
　～ incredibly　令人难以置信地发生
　～ marvelously　不可思议地发生
　～ normally　正常举行
　～ occasionally　偶尔发生
　～ phenomenally　非凡地举行
　～ readily　很快地举行
　～ sporadically　不时地发生

　Such a thing hardly ever occurs.　这样的事几乎不发生。
　A leap-year occurs at every four years.　闰年每4年一次。
　His birthday occurs on 9th May.　他的生日是5月9日。
　It occurs more often in women than in men.　此事更经常发生在女性身上，较少地发生在男性身上。
　The explosion occurred during an exercise near the town.　在离市镇不远的地方演习时发生了爆炸。
　These plants occur only in tropics.　这些植物只生长在热带。
　That sound doesn't occur in his language so it's difficult for him to pronounce.　他的语言里没有那个音，因此他很难发出。
　Misprints occur on every page.　每一面都有印刷错误。
　The word "gratitude" did not occur on Napoleon's personal dictionary.　“感激”两字在拿破仑私人词典中是见不到的。
　Few metals occur free.　金属呈游离态的很少。
　Silver occurs natural.　银是天然存在的。

 ♣ occur to　(v.+prep.)
1. …发生在 happen to sb (especially of unpleasant events)
　I hope no accident has occurred to him.　我希望他没出什么事。
2. 被想起〔到〕 come to mind of (sb/sth)
　Such a simple explanation never occurred to me!　我从未想到如此简单的解释。
　A wonderful idea occurred to him.　他突然想到一个妙主意。
　As soon as that thought occurred to him, he felt worse.　一想到那一点，他的心情就变糟。
　It occurred to my mind.　我当时想到了这件事。
　His name did not occur to my memory.　我当时没有想起他的名字。
　Didn't it occur to you to close the window?　难道你没有想到去关窗户吗?
　Didn't it occur to you to phone them about it?　关于这件事你难道就没想到给他们打个电话?
　It occurred to him to tell the colonel of the problem.　他想起要告诉上校那个问题。
　It never occurred to me not to endeavor to do so; I was politically minded by nature.　我从来没有想到过要打退堂鼓，我天生就是搞政治的。
　It occurs to me that example is always more efficacious than precept.　我想到身教重于言教。
　Has it ever occurred to you that this old book might be of great value?　你想到没有，这本旧书或许有很大的价值?
　It never occurs to me that he was only acting a part.　我从来没有想到，他只是在弄虚作假。
　It never occurred to me that I had seen her before somewhere.　我想不起来以前我在哪儿见过她。
　Did it occur to him that lookers-on see most of the game? 　他可曾想到旁观者清吗?
　It occurred to me that I had left the door unlocked.　我忽然想起来忘了锁门了。
　It occurred to her that she might adopt a homeless child.　她可能想收养一个无家可归的孩子。
　It occurred to him that he hadn't eaten anything since the night before.　他想起他自前天晚上以来一点东西没吃。
　It never occurred to me for a moment you meant that.　我一点儿也没想到你是这个意思。

 ♣ occur, happen, take place
　参见happen条。

1. 我突然想起我还没有及时交论文。
　［误］ It occurred me suddenly that I had not handed in my paper.
　［正］ It occurred to me that I had not handed in my paper.
　［析］ occur是不及物动词，后面不能直接接宾语，表示“…被某人想起”，应该用It occurs〔occurred〕 to sb结构。另外， occur也不与suddenly连用。
2. 会发生第三次世界大战吗?
　［误］ Do you think there will occur a World War III?
　［正］ Do you think there will be a World War III?
　［析］ “发生战争”一般不用occur，而用be.

　［同义词］ appear, arise, befall, chance, come about, develop, exist, happen, obtain, result
　［词源］　拉丁语occurrere（跑来）