If headaches only occur at night, lack of fresh air and oxygen is often the cause. [VERB]

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。

The crash occurred when the crew shut down the wrong engine. [VERB]

机务人员关错了引擎，随即飞机坠毁。

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。

The cattle disease occurs more or less anywhere in Africa where the fly occurs. [VERB adv./prep.]

在非洲凡是有这种蝇虫的地方，几乎都会出现这一牛病。

These snails do not occur on low-lying coral islands or atolls. [VERB adv./prep.]

在地势低平的珊瑚岛或环礁上没有这种螺。

It did not occur to me to check my insurance policy. [V to n to-inf]

我没有想到要核实我的保险单条款。

It occurred to me that I could have the book sent to me. [it V to n that]

我想到可以让人把书寄给我。

The same idea had occurred to Elizabeth. [VERB + to]

伊丽莎白也想到了这个主意。