becomes so worn and unreliable that it eventually is not worth mending.
磨損太厲害，老得一點兒也不準了，最終會不值得修理了。
新概念英語第四冊
Lesson 37 The process of ageing
?? 句中詞匯解析
從本句中提取的重要詞匯
adv. 終于，最后;竟;總歸;終究;
?? eventual最后的+ly 表示方式、程度、狀態、“...地” → ad.終于；最后
"Eventually, his anger dissipated."
他的憤怒終于平息了。
近義：sometime, lastly, ultimately, finally
adj. 穿舊的，用舊的;穿壞的，用壞的;筋疲力盡的;
v. wear的過分詞;
"the replacement of worn car parts"
汽車上損壞零件的更換
近義：outworn, pined, shabby, threadbare, torn, undermined
反義：modern, new, novel, recent, unused
adj. 值得的;有…的價值;等值的;有…的財產;
n. 財富，財產;價值;
"Each answer is worth 20 points."
每題為20分。
近義：merit, price, pricing, rate, value, worthiness
反義：insignificance, slightness, insignificancy
unreliable
[[??nri'lai?bl]]
a. 不可靠的\\n[法] 不可靠的, 靠不住的
近義：inconstant, nondependable, skittish, undependable, untrustworthy, wanton
反義：occasioning, reliable, sedate, serious, staid, sure