Euclid was a Greek mathematician who lived around 300 BC. He wrote a long set of books called the Elements, in which he started from a few clear rules and then proved, step by step, how lines, angles, and shapes fit together.

Euclid was歐幾里得是a Greek mathematician一位希臘數學家who lived around 300 BC活在西元前300年左右。He wrote a long set of books called the Elements他寫了一整套書，叫做《幾何原本》，in which he started from a few clear rules書裡他從幾條清楚的規則出發，and then proved, step by step然後一步一步證明how lines, angles, and shapes fit together線、角和形狀是怎麼組合在一起的。

The ordinary geometry you meet at school — parallel lines that never meet, a triangle whose three angles add up to 180 degrees — is still called Euclidean geometry, after him. Later mathematicians found other geometries that do not follow those rules, so “Euclidean” now also marks the familiar kind as against those stranger ones.

The ordinary geometry you meet at school你在學校學到的一般幾何— parallel lines that never meet, a triangle whose three angles add up to 180 degrees — 平行線永遠不會相交，三角形三個角加起來是180度is still called Euclidean geometry, after him仍然以他為名，叫做歐氏幾何。Later mathematicians found other geometries後來的數學家發現了其他幾何that do not follow those rules不遵守這些規則so “Euclidean” now also marks所以『歐氏』現在也用來標示the familiar kind as against those stranger ones我們熟悉的這一種，跟那些比較奇特的幾何做區分。

We say the name YOO-klid.

We say the name我們把這個名字唸作YOO-klidYOO-klid。

It is a person’s name used as a label for a whole way of thinking about space, not a common noun you pluralise.

It is a person's name這是一個人名used as a label for a whole way of thinking about space被拿來當作一整套空間思考方式的標籤not a common noun you pluralise不是可以加s變複數的普通名詞。