pandemics例句

Periods when diseases spread around the world are called pandemics.
疾病在全世界范围内传播时期称为大流行.

Since then, there have been a total of eight cholera pandemics.
从那时开始, 霍乱大流行总共爆发过8次.

Previous pandemics have been characterized by waves of activity spread over months.
以往大流行的特点是一波接一波的流行持续数月之久.