Over a period of time

• 过了一段时间

Over a period of time的用法和样例：

例句

1. An increase in the incidence of oxacillin-resistant S. aureus oer time was obsered.
   并且经过一段时间的观察发现耐苯唑西林的金葡菌的比例有所增加。
2. The clean wool is then spun by hand.The wool is loosely dipped into dyeing vats and left for a time that could be judged only by the expert craftsman.
   漂染的过程是在染桶里进行的，将稀松的毛线放在染桶里保持一段时间，而只有专业的工匠才能把握好这段时间的长短。