有朋友在後臺問我關於這幾個詞的區別，於是我在網上找到了一篇解釋的比較好的內容，轉載來分享給大家。
詞義辨析
1、enough 和sufficient 在含義上幾乎沒有差異，指「充分的；足夠的」，表示數量完全滿足需要或期望。一般enough 比sufficient 使用更普遍。而在用法上，enough 後面既可以加可數名詞也可以加不可數名詞。如：enough people 足夠人數；enough money 足夠的金錢。而sufficient 後面一般只能加不可數名詞。如：sufficient sunlight, water and oxygen 充足的陽光、水和氧氣；sufficient investigation 充分調查。但也可以用於少數可數名詞，如：sufficient funds 足夠的資金；sufficient foreign exchange reserves 足夠的外匯儲備。
2、adequate 雖然也表示「足夠的；充分的」，但是與enough 和sufficient 二詞之間有著細微差異。
主要體現在以下兩點：
(i) adequate 的內涵是：合理的、公平的或不苛刻的，在主觀上並不一定是讓人滿足的，有時往往指滿足一個最低或客觀標準。如：His wages are adequate to support three people. 這句話說的是：他的工資夠養活3個人的。即，這些錢養活3個人夠得上一般生活水平。但這些錢可能並不能滿足他心理的期望。 而，He has enough money to spend. 他有足夠的錢讓他去花。 即，表示他的錢完全能夠滿足他的需要。
(ii) adequate 在表示「充分、足夠」時包含了「公平、合理、適當」的意思，其並不單單指數量，更傾向於表示質量、標準或要求。如：adequate compensation 適當補償；adequate remedy at law 法律上的充分救濟；adequate manning 充分的船員配備；adequate disclosure 充分披露。因此在指數量上的足夠時，一般用enough 或sufficient 。
例句展示
從如下例句中可以看出三個詞之間的細微差別： The pay was adequate, but it certainly wasn’t generous. The rate of pay was barely adequate to raise a family on. His answer to the question was adequate but it wasn’t developed sufficiently to gain high marks. The Prime Minister gave an inadequate reply to the journalist’s question. There were not enough seats for all the guests. The supply of seats was quite inadequate. There was enough food for everyone. There was a sufficient amount of food. There was insufficient evidence to convict him of house-breaking.
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