costly學測 L3KK [ˈkɑstli] ｜ /ˈkɑstli/
昂貴的；費用高的·代價大的；損失大的
學測常考，易與cost詞性混淆
The school trip to Japan was too costly, so many students stayed home instead.
學校的日本畢業旅行太貴了，許多學生只好留在家裡。
一個畫面：荷包大失血
掏錢心痛付出大筆金錢時忍痛的感覺
重大犧牲為了達成目的付出慘痛代價
義項
掏錢心痛C1adjective昂貴的；費用高的
A new laptop can be costly, so I saved money for six months before buying one.
一台新筆電可能很貴，所以我存了六個月的錢才買下一台。
costly repairsa costly vacation
重大犧牲C1adjective代價大的；損失大的
Losing the game was costly for the team because their best player got hurt.
輸掉比賽的代價很大，因為隊上最好的選手受傷了。
a costly mistakea costly delay
片語
a costly mistake代價慘痛 →造成嚴重損失的錯誤
costly repairs維修燒錢 →修理費用非常高
prove costly後果慘重 →後來證實代價很大
你會不會這樣說？
The repair turned out to be very ___. (costly / cost)
看答案
costly
costly 是形容詞，cost 是名詞或動詞，此處需要形容詞。
'Losing the game was costly for the team because their best player got hurt.' 這裡 costly 最接近哪個意思？(A) 昂貴的 (B) 代價大的
看答案
(B)
此句描述輸球造成的重大損失，對應「代價大的」義項而非價格。
字族
cost 費用；花費（名詞或動詞）
順路看看
expensive — 與 costly 意思相近，日常更常用cheap — costly 的反義詞，價格低廉affordable — 負擔得起，是 costly 的反面感受多益練習
本區為多益情境練習，與上方釋義獨立編寫
情境例句
辦公設備
Replacing all the office printers at once would be costly.
一次更換辦公室所有印表機會所費不貲。
專案失誤
Deleting the design files was a costly mistake that set the team back two weeks.
刪除設計檔案是個代價很大的錯誤，讓團隊的進度落後了兩週。
詞族
cost 名詞／動詞 費用；花費・costly 形容詞 昂貴的；代價大的・costlier 形容詞比較級 更昂貴的；代價更大的・costliest 形容詞最高級 最昂貴的；代價最大的
四選一
Replacing the entire printing system would be too ____ for our small office.
看答案
costly
be too 後需要可表示程度的形容詞，costly 表示費用過高。cost 與 costs 作名詞或動詞都不合此結構；costing 即使作分詞或名詞，也無法在此處表示「太昂貴」。
同義改寫
Replacing all the office printers at once would be costly. → Replacing all the office printers at once would be expensive.
此處 costly 指更換設備的費用高，與 expensive 等義。
Deleting the design files was a costly mistake that set the team back two weeks. → Deleting the design files was a mistake with serious consequences that set the team back two weeks.
此處 costly 指錯誤造成重大代價；改寫保留嚴重後果及進度落後兩週的具體損失，不另行推定金錢損失。