cold(ness)
1.cold（名词）和coldness略有不同。cold是“寒冷”，尤其指天气的“寒冷”，如The cold is intense和Do you feel the cold?coldness是“寒冷性”或“冷淡性”，如the coldness of the weather和the coldness of his reception。
2.cold（伤风）和cold in the head没有区别。
3.catch cold和catch a cold都可以说。have a cold里必须有a。take cold里没有a，但take a bad cold, take a heavy cold等表达方式里必须有a。get a cold比get cold普通。
