forest that has grown back after the original forest was harvested or destroyed; second growth

to become familiar with something or someone after repeated exposure; strangers at first meeting soon become friends

Pollution caused by new harmful substances that are created when pollutants released from a source undergo chemical or biological changes in the environment; also called [[二次污染|二次汙染|er4 ci4 wu1 ran3]]

A secondary disaster triggered by a primary natural or man-made event, such as a fire or disease outbreak following an earthquake