And any given odorant, like this pizza, is made up of hundreds of different chemicals that you can smell, like the thymol of the oregano, the butyric acid of the cheese, and the acetylpyrazine of the crust.

定气味，比如这个披萨，是由你能闻到数种不同化学物质组成，比如牛里香酚，奶酪丁酸，和外皮乙酰吡嗪。