adequate

Compared meaning: as much as is needed (adjective).

比较义项：数量上充足、满足需要（adj.）。

• enough

  The most common, neutral word for this idea, used freely in speech and writing; it can also work as an adverb or pronoun, unlike the other two.

  这是表达这一概念最常见、语气中性的词，口语和书面语中都很常用；它还可以作副词或代词使用，这一点是另外两个词做不到的。

  Do we have enough chairs for everyone at the party?

  我们有足够的椅子给聚会上的每一个人坐吗？

• sufficient

  More formal than enough, typical of written, academic or official contexts, and often specifies the purpose something is needed for.

  比enough更正式，常用于书面语、学术或公文语境，并常说明所需满足的具体目的。

  The committee ruled that the evidence was sufficient to proceed with the case.

  委员会裁定证据足以推进这起案件的审理。

• adequate 本词

  Formal like sufficient, but stresses meeting a minimum acceptable standard rather than being generous; common when judging quality, funding or performance.

  和sufficient一样正式，但强调达到最低可接受标准而非充裕；常用于评价质量、资金或表现是否达标。

  The old wiring is no longer adequate for the building's power needs.

  这栋楼老旧的电线已不足以满足该建筑的电力需求。

Enough, sufficient, and adequate all mean having enough for a need. Enough is the most common word, and can also be an adverb or pronoun. Sufficient is more formal, used in academic or official writing. Adequate is also formal, but stresses meeting a minimum standard.

这三个词在这个意义上都表示“数量上足够”，学习者容易混淆，但正式程度和使用场合不同：enough最口语化，sufficient和adequate更正式，其中adequate还常强调“刚好达到最低标准”而非充裕。此外，enough在英语里也可以作副词或代词使用，但这里只比较它的形容词义项。