葱是一种非常常见的调味料，在中餐和世界其他地方都有广泛的应用。它的气味是什么呢？我们可以用英语来描述。

Onion is a very common seasoning that is widely used in Chinese cuisine and other parts of the world. Its smell is very distinctive and pungent. When you cut into an onion, it releases a strong and sharp odor that can make your eyes water. Some people find this smell unpleasant, while others enjoy it.

The smell of onion comes from a compound called syn-propanethial-S-oxide, which is released when the onion is cut or crushed. This compound is what gives onion its distinctive aroma and flavor. It is also the reason why your eyes water when you cut into an onion, as the compound can irritate the eyes.

Despite its pungent smell, onion is a very versatile ingredient that can be used in a variety of dishes. It adds flavor and depth to soups, stews, and sauces, and can also be used raw in salads and sandwiches. Some people even enjoy eating raw onions on their own, although this can be an acquired taste.

Overall, the smell of onion is a defining characteristic of this popular seasoning. Whether you love it or hate it, there's no denying that onion adds a unique and delicious flavor to many different kinds of food.