31.(Error Correction ) In choosing between two alternate sets(A ) of pleasure one could not necessarily decide which(B ) was preferable by an arithmetical calculation, nor could(C ) one necessarily do so even if(D ) one was omniscient.

當形容詞用的 alternate意為「(日期、星期等) 間隔的，每隔的；交替的，輪流的」，如 They saw each other on alternate Sundays. (他們每隔一個星期天相會一次)；According to the weather forecast, there will be a week of alternate rain and sunshine. (根據天氣預報，下禮拜時雨時晴)。當名詞用的 alternate意為「代理人；代替者；候補者」，如 She was appointed an alternate, not a full delegate. (她被任命為代理代表，而非正式代表)；We have several alternates on our team. (我們隊有幾名替補隊員)。

當形容詞用的 alternative意為「兩者 (或若干個) 中擇一的；替代的；供選擇的」，如 We are now looking for an alternative venue. (我們正在找一個替代會場)。然而，alternative的「替代的；供選擇的」意思現在似乎逐漸被 alternate 所取代： They gave us an alternate [alternative] plan/suggestion. (他給我們一項替代計畫/建議)。alternate 和 alternative 的這項意思都是標準英語。

不知道是不是考這個觀念，有請強者解答