occur

verb

1. 发生；出现
   to happen
   1. When exactly did the incident occur?
      这一事件究竟是什么时候发生的？
   2. Something unexpected occurred.
      发生了一件出乎意料的事。
2. 存在于；出现在
   to exist or be found somewhere
   1. Sugar occurs naturally in fruit.
      水果天然含糖分。

1. VERB 发生
   When something occurs, it happens.
   1. If headaches only occur at night, lack of fresh air and oxygen is often the cause...
      如果只是在晚上头疼，那常常是由于缺乏新鲜空气和氧气的缘故。
   2. The crash occurred when the crew shut down the wrong engine...
      机务人员关错了引擎，随即飞机坠毁。
   3. In March 1770, there occurred what became known as the Boston Massacre.
      1770年3月在那里发生了后来闻名的波士顿惨案。
2. VERB 存在；出现；有
   When something occurs in a particular place, it exists or is present there.
   1. The cattle disease occurs more or less anywhere in Africa where the fly occurs...
      在非洲凡是有这种蝇虫的地方，几乎都会出现这一牛病。
   2. These snails do not occur on low-lying coral islands or atolls.
      在地势低平的珊瑚岛或环礁上没有这种螺。
3. VERB （想法或主意）被想到，被想起，浮现于脑海中
   If a thought or idea occurs to you, you suddenly think of it or realize it.
   1. It did not occur to me to check my insurance policy...
      我没有想到要核实我的保险单条款。
   2. It occurred to me that I could have the book sent to me...
      我想到可以让人把书寄给我。
   3. The same idea had occurred to Elizabeth.
      伊丽莎白也想到了这个主意。

1. Changes in temperature occur slowly and are constrained within relatively tight bounds.
   温度变化缓慢，而且局限在相对较小的范围内。
2. There will come a time when the crisis will occur.
   危机总有一天会爆发。
3. Ulcers occur when the stomach's natural acids eat into the lining of the stomach.
   胃酸侵蚀胃内壁引发溃疡。
4. Such events occur only when the external conditions are favorable.
   这种事情只有在外部条件有利时才会发生。
5. When vacancies occur, the office puts out feelers to the universities.
   有空缺职位的时候，办事处就到各个大学去打探。
6. Unless you respect other people's religions, horrible mistakes and conflict will occur.
   如果不尊重别人的宗教信仰，就会祷下大错，酿成冲突。
7. Curiously, the word 'gay' does not occur in the index
   奇怪的是，gay这个词没有出现在索引当中。
8. If the climate gets drier, then the logical conclusion is that even more drought will occur
   如果气候变得更干燥，必然会出现更多旱情。
9. Emergency cooling systems could fail and a reactor meltdown could occur.
   紧急冷却系统有可能失灵，核反应堆有可能发生堆芯熔毁。
10. High levels of nitrate occur in eastern England because of the heavy use of fertilizers.
    英格兰东部因大量使用化肥导致土壤硝酸盐浓度过高。
11. If headaches only occur at night, lack of fresh air and oxygen is often the cause
    如果只是在晚上头疼，那常常是由于缺乏新鲜空气和氧气的缘故。
12. The crash occurred when the crew shut down the wrong engine
    机务人员关错了引擎，随即飞机坠毁。
13. In March 1770, there occurred what became known as the Boston Massacre.
    1770年3月在那里发生了后来闻名的波士顿惨案。
14. The cattle disease occurs more or less anywhere in Africa where the fly occurs
    在非洲凡是有这种蝇虫的地方，几乎都会出现这一牛病。
15. These snails do not occur on low-lying coral islands or atolls.
    在地势低平的珊瑚岛或环礁上没有这种螺。
16. It did not occur to me to check my insurance policy
    我没有想到要核实我的保险单条款。
17. It occurred to me that I could have the book sent to me
    我想到可以让人把书寄给我。
18. The same idea had occurred to Elizabeth.
    伊丽莎白也想到了这个主意。
19. Although it is predominantly a teenage problem, acne can occur in early childhood
    虽然粉刺多发于青少年时期，但也可能在刚进入童年时期就出现。
20. I have known dramatic changes occur in the space of a few minutes with this method.
    我知道用这种方法短短几分钟之内就能够产生急剧的变化。
21. Dryness at the roots can occur very easily specially when plants are grown in containers.
    根部很容易干枯，特别是当植株被种养在盆中时。
22. No one has suggested how this might occur
    没人说得清这事是怎么发生的。
23. If these drugs are stopped abruptly then some withdrawal symptoms may occur.
    如果突然停服这些药，则可能出现一些戒断症状。
24. The time when a solar eclipse will occur can be calculated.
    日食发生的时间可以推算出来。
25. Food shortages often occur in time of war.
    在战争期间常常发生粮食短缺的情形。
26. Frosts often occur in November.
    11月份经常出现霜冻。
27. Whilst the detoxification requires energy, slow decay may still occur.
    由于解毒作用需要能量，所以缓慢的腐朽仍然会发生。
28. Many nematodes occur in the tissues of earthworm.
    蚯蚓组织中有许多种线虫。
29. Complementation between viruses may occur, owing to the interaction between their gene products.
    病毒与病毒之间由于它们的基因产物相互作用的结果能发生互补。

  happen occur take place【导航词义：发生】

  happen v. 发生

〔辨析〕普通用词，多用于偶然事件。

  occur v. 〈正式〉发生

〔辨析〕可用于偶然事件或计划之事，可与 happen 换用。

  take place phr. v. 发生，举行

〔辨析〕主要用于事先计划好的事情。

occur to sb

1. 被想到；出现在头脑中
   to come into your mind
   1. When exactly did the incident occur?
      这一事件究竟是什么时候发生的？
   2. Something unexpected occurred.
      发生了一件出乎意料的事。

verb

1. come to pass
   1. What is happening?
   2. The meeting took place off without an incidence
   3. Nothing occurred that seemed important

   Synonym:    happenhapgo onpass offpassfall outcome abouttake place

2. come to one's mind
   1. It occurred to me that we should hire another secretary
   2. A great idea then came to her

   Synonym:    come

3. to be found to exist
   1. sexism occurs in many workplaces
   2. precious stones occur in a large area in Brazil