A capillary is the smallest kind of blood vessel in the body — a tube so thin it is like a hair. Arteries bring blood from the heart, veins take it back, and capillaries are the net in between. Through their thin walls, oxygen and food slip out into the cells, and waste slips back in.

A capillary is the smallest kind of blood vessel in the bodycapillary微血管是人體裡最細小的血管 a tube so thin it is like a hair一條細到像頭髮的管子 Arteries bring blood from the heart動脈把血液從心臟帶出去 veins take it back靜脈把血液帶回來 and capillaries are the net in between而capillary就是中間那張網 Through their thin walls透過它們薄薄的管壁 oxygen and food slip out into the cells氧氣和養分會滲出到細胞裡 and waste slips back in廢物則會滲回來

You cannot see them the way you see a vein on your wrist. If a line stands out on your hand, that is a vein, not a capillary.

You cannot see them你沒辦法看到它們 the way you see a vein on your wrist像看到手腕上的靜脈那樣 If a line stands out on your hand如果你手上有一條線凸出來 that is a vein, not a capillary那是靜脈，不是capillary

The same “thin as a hair” idea turns up in science class as capillary action: liquid climbing up a very thin tube by itself, even against gravity. That is how a paper towel drinks a spill, how ink finds a pen nib, and how water can rise in soil.

The same "thin as a hair" idea turns up in science class同樣細如毛髮的概念在自然課裡會出現 as capillary action變成capillary action毛細現象 liquid climbing up a very thin tube by itself液體會自己順著一條很細的管子往上爬 even against gravity甚至逆著重力 That is how a paper towel drinks a spill這就是為什麼廚房紙巾能吸掉灑出來的水 how ink finds a pen nib墨水能找到筆尖 and how water can rise in soil以及水能在土壤裡往上升的原因

Though actually, people say capillary action far more than they say a capillary tube in ordinary life. The “hair” picture is hiding in the Latin, not in the English spelling, so nobody guesses it without being told. This is not a fancy word for hair, and it is not a large vein.

Though actually不過其實 people say capillary action far more than they say a capillary tube in ordinary life日常生活裡大家說capillary action的頻率遠高於說a capillary tube The "hair" picture is hiding in the Latin毛髮這個畫面藏在拉丁字源裡 not in the English spelling不是藏在英文拼法裡 so nobody guesses it without being told所以沒有人聽人講就能猜到 This is not a fancy word for hair這不是頭髮的花俏說法 and it is not a large vein也不是指大條的靜脈