Two fractions cannot be added while their pieces are different sizes. So you look for one number that every bottom number fits into, cut everything into pieces of that size, and suddenly the fractions can sit side by side. That is the whole picture: the one thing underneath that works for all of them. English then carries that picture out of the maths class. Put several people or stories side by side and the thing found underneath all of them is the common denominator — and if you go as low as you must to fit everybody in, you get the lowest one.
兩個分數的份數大小不一樣，就加不起來。所以要找一個數字，讓每個分母都能整除。把每個分數都改寫成那樣大小的份數，它們就能放在一起算了。這個畫面可以一路帶著走：底下那個「大家都通得過」的東西。把幾個人或幾件事並排放，底下共通的那一點，就是 common denominator。而如果為了把每個人都塞進去，一路往下降到不能再低，那就是 the lowest common denominator。
登入就可以看每一支怎麼連回核心畫面。