Inside a rat's nose are up to 1,000 different types of olfactory receptors whereas humans only have 100 to 200 types.
2017年12月四级真题（第一套）阅读 Section A
Rats are often associated with spreading disease rather than preventing it, but this long-tailed animal is highly sensitive Inside a rat's nose are up to 1, 000 different types of olfactory receptors whereas humans only have 100 to 200 types.
2017年12月四级真题（第一套）阅读 Section A
柯林斯高阶英汉双解学习词典释义
ADJ
嗅觉的
Olfactory means concerned with the sense of smell.