英语语法分析

It has long been known that the level of serum iron in animals falls during infection.

人们早就知道，在感染期间，动物的血清铁水平会下降。

One family of completely harmless snakes, the kingsnake, has also evolved serum that neutralizes rattlesnake venom.

一种完全无毒的蛇家族，王蛇，也进化出了能中和响尾蛇毒液的血清。

The virus was first identified in the State Serum Institute in Copenhagen, Denmark, in 1958 during an investigation into a pox-like disease among monkeys.

1958年，在对一种猴子中出现的痘类疾病的调查中，丹麦哥本哈根的国家血清研究所首次发现了这种病毒。