occur的例句（occur在句子中的用法）

• About two in every five epileptic fits occur during sleep... 每5例癫痫病中约有两例是在睡眠过程中发作的。
• 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。
• 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。
• 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。