increase by 與 increase to：一個小介系詞，數字就跑掉
某位學生在商業英文課上報告季度圖表。她得意地說：「Sales increased to twenty thousand dollars, from twenty thousand to forty thousand.」老師停了一下，微笑問：「所以新的總額是兩萬還是四萬？」學生愣住了。她想表達的是「差距是兩萬」——但 to 這個字悄悄告訴整個教室完全不同的訊息。一個小小的介系詞，整段數字的邏輯就崩了。
為什麼這件事重要
每當有人在讀圖表、報告調薪、描述價格變動或講氣溫上升時，你都會聽到 increase by 與 increase to。同樣的用法也會出現在 rose、grew、climbed、dropped、fell、decreased 與 declined。在會議裡，介系詞用錯，可能把小幅變動講成大幅，或反過來。在寫作或口說考試裡，考官會特別聽這個區別，因為它顯示你會不會精確描述資料。規則很短，但講錯的代價很大。
如果你已經讀過 percent、percentage 與 percentage points：小字差一字，意思差很多，就已經看過一個小字怎麼把微幅變化講成巨幅變化。by 跟 to 的差別也是一樣的邏輯，只是換成絕對數字而非比例。
用法規則
increase by 描述變動的幅度，也就是舊值與新值之間的差距。
- Sales were one hundred. They increased by twenty. New total: one hundred and twenty.
- Her salary rose by ten percent. 如果她原本領五萬，現在領五萬五。
- The temperature dropped by five degrees overnight.
increase to 描述新的值本身，告訴你數字最後落在哪裡，而不是跳了多大。
- Sales increased to one hundred and twenty.（只看這句，我們並不知道原本的數字。）
- Her salary rose to fifty-five thousand.（我們知道她現在領五萬五。）
- The temperature dropped to five degrees.（現在是 5 度，不管之前是幾度。）
同樣的邏輯也適用於 decrease、fall、drop、decline、shrink、rise、climb 與 go up / down。
還有一個非常實用的第三種型態：from X to Y，一句話就把兩個端點都講出來。
- Sales rose from one hundred to one hundred and twenty.
- The rate dropped from eight percent to five percent.
用 from … to … 時就不需要 by——差距已經隱含在裡面。把 by 跟 from / to 混用是最常見的失誤。
錯誤／自然／為什麼
| 錯誤 | 自然 | 為什麼 |
|---|---|---|
| Sales increased to 20%, from 30% to 50%. | Sales increased by 20 percentage points, from 30% to 50%. | 差距的「幅度」要用 by，不是 to。 |
| The price rose by 50 dollars, to 200 dollars from 150. | The price rose by 50 dollars, from 150 to 200. | From X to Y 是一組固定搭配，不要被 by 拆開。 |
| Our team grew to 5 members last quarter (we had 8, now we have 13). | Our team grew by 5 members last quarter, from 8 to 13. | Grew to 5 會被理解成「最後總數是 5」，不是差距。 |
| The temperature dropped by 10 degrees, from 25. | The temperature dropped by 10 degrees, from 25 to 15. | 如果提到起點，搭配 to 講出終點會比較清楚。 |
| Profits increased by to 2 million. | Profits increased to 2 million. | By 與 to 不能疊在一起；只能擇一。 |
| Unemployment fell to 1 percentage point. | Unemployment fell by 1 percentage point. | 那個 1 點是「下降的幅度」，不是「新的比率」。 |
| Her score went up by 95 out of 100. | Her score went up to 95 out of 100. | 如果 95 是新的總分（不是差距），就要用 to。 |
| The rent increased on 100 dollars. | The rent increased by 100 dollars. | 英文用 by 表示變動的幅度，不是 on。 |
| Revenue increased of 10% this year. | Revenue increased by 10% this year. | 動詞片語中表示變動幅度不用 of。 |
常見情境
讀銷售圖表。「Revenue rose by about fifteen percent this quarter, from four million to roughly four point six million.」注意 rose by 帶出幅度，from … to … 點出端點。兩者搭配，一句話同時報告幅度與終值。
討論薪水。「I got a raise — my pay went up by eight percent.」這是告訴朋友調薪的幅度。如果說「my pay went up to eighty thousand」，是在告訴對方新的數字。兩句都可能同時為真，但回答的是不同的問題。
考試分數進步。 家教說：「Your reading score improved by five points, from twenty-two to twenty-seven.」如果只說「improved to twenty-seven」，學伴並不會知道你進步了多少。兩個數字一起講才能把故事說完整。
氣象報告。「Overnight, temperatures dropped to about three degrees Celsius, a fall of roughly seven degrees from yesterday's high.」注意這裡的名詞用法小技巧：a fall of seven degrees 用 of，因為 fall 是名詞而不是動詞。當動詞用時就要說「fell by seven degrees」。
匯率與物價變動。「The euro strengthened by two cents against the dollar, climbing to one point ten.」財經報導幾乎一定把變動幅度跟新的水準一起講。下次聽市場新聞時，特別注意 by … to … 這個搭配。
常見錯誤
- 想表達「變動幅度」時誤用 to：例如「Sales increased to ten percent」，但實際是上升了原本基數的 10%。
- 把 by 跟 to 疊在一起：increased by to ten percent 永遠是錯的。
- 忘了還有 from … to … 這個結構，可以一句話把兩個端點都講清楚。
- 在表示變動的動詞後用 of。「Increased of ten percent」是錯的，要用 by。但名詞形（an increase of ten percent）就可以用 of。
- 把 percentage points 跟 percent 在「差距」上搞混。如果失業率從 4% 變成 6%，那是上升 by two percentage points，不是 by two percent。
- 不小心說成 increased on 或 increased in。In 可以用在時間範圍（「in the third quarter」），但不能用在變動幅度上。
- 完全省略介系詞：「Sales increased ten percent」在新聞文體可接受，但在仔細的口語英文裡，「increased by ten percent」會更清楚。
小練習
填入 by、to，或 from / to——並確認數學邏輯有對。
- The number of users grew ______ five hundred ______ eight hundred this month.
- Our delivery time dropped ______ thirty minutes; it used to be ninety, and now it is sixty.
- The temperature climbed ______ thirty-five degrees Celsius by noon, the highest reading of the week.
- Inflation rose ______ half a percentage point, from two percent ______ two point five percent.
- The rent on this apartment went up ______ a hundred and fifty dollars this year.
總結
increase by 是變動的幅度。increase to 是數字最後落在哪裡。from X to Y 用一句優雅的話同時點出旅程的兩個端點。要講差距就用 by，要講新值就用 to，想一句話把所有資訊講完就用 from … to …。一旦這三個用法變成直覺反應，你的資料句子就不會再讓聽者搞錯方向——也不會在每個要你描述圖表的考試裡被扣分。
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