occur to sb (that...)
常用于 it occurs to sb that... 结构，表示某人想到某事。
It occurred to me that I had left the door open.
我突然想到我忘了关门。
发生
occurring — present participle of occur
想到；想起；存在；出现；呈现；出现；呈现。
发生。
To happen or take place.
出现；呈现。
To present or offer itself.
被想到；浮现于脑海。
To come or be presented to the mind; to suggest itself.
存在；被发现。
To be present or found.
一般现在时
Accidents often occur on this road.
事故经常在这条路上发生。
past
The accident occurred yesterday.
事故昨天发生了。
现在进行时
Changes are occurring rapidly.
变化正在迅速发生。
规则动词，注意拼写变化（双写 r）。
The accident occurred at the intersection of Main Street and First Avenue.
事故发生在主街和第一大道的交叉口。
用法提示：动词过去式，表示‘发生’
A strange thought occurred to me while I was waiting for the bus.
我在等公交车时突然产生了一个奇怪的想法。
用法提示：动词过去式，表示‘（想法）浮现于脑海’
How often does this type of error occur in the system?
这种类型的错误在系统中多久发生一次？
用法提示：动词原形，在疑问句中表示‘发生’
常用于 it occurs to sb that... 结构，表示某人想到某事。
It occurred to me that I had left the door open.
我突然想到我忘了关门。
The accident occurred at 8 pm.
事故发生在晚上8点。
Such events occur rarely.
这类事件很少发生。
happen是occur最常用的同义词，口语和书面语皆可；occur稍显正式。
take place常指有计划或安排的事情发生，occur则更通用。
come about强调事情发生的方式或过程，较为正式。
arise多指问题、情况等发生或开始出现，常与from连用。
grammar · medium
易错句子The accident occurred him yesterday.
正确表达The accident happened to him yesterday.
动词 occur 是不及物动词，不能直接带宾语，表示事件发生时应使用 happen to sb。
grammar · medium
易错句子I occurred a good idea.
正确表达A good idea occurred to me.
occur 表示“想到”时需加介词 to，主语应是想法而非人。
occur 较正式，常用于具体事件或想法；happen 更常用，多指偶然或意外发生。
take place 常指有计划或安排好的事件；occur 可指任何事件或现象，可替换性较强但语气不同。
想到；想起
It didn't occur to me that you were waiting.
我没有想到你在等。
出现在；存在于
These minerals occur in many regions.
这些矿物出现在许多地区。
发生在（某个时间或地点）
The accident occurred at 3 p.m.
事故发生在下午3点。
发生在...期间
Several changes occurred during the meeting.
会议期间发生了几个变化。
当...时发生
Problems occur when the system is overloaded.
当系统过载时会出现问题。
频繁发生
Earthquakes occur frequently in this region.
这个地区地震频繁发生。
与"发生"相关，事件是发生的事物
与"出现"相关，现象是观察到的事物
与"想起"相关，想法是出现在脑海中的
与"存在"相关，存在是出现的一种状态
与"出现"相关，强调从隐藏到可见
某人想到
It never occurred to me that he might be lying.
我从未想到他可能在撒谎。
Dictionary facts from ECDICT, WIKTIONARY.