sustain

Compared meaning: keep something going or unchanged (verb).

比较义项：维持，使保持原状或持续（动词）。

• maintain

  Maintain emphasizes ongoing care or effort to keep something in good condition or unchanged, often used for households, equipment, standards, or relationships.

  maintain强调通过持续的照料或努力，使某物保持良好状态或维持不变，常用于家庭、设备、标准或人际关系等。

  It takes effort to maintain a clean house with three kids.

  带着三个孩子，想维持一个整洁的家需要付出努力。

• sustain 本词

  Sustain emphasizes keeping something alive or continuing despite difficulty, pressure, or scarce resources, often used for crops, life, or economies.

  sustain强调在困难、压力或资源匮乏的情况下使某事物得以维持或延续，常用于农作物、生命或经济等。

  Farmers work hard to sustain their crops during dry seasons.

  农民们在干旱季节努力维持农作物的生长。

Maintain and sustain both mean to keep something going. Maintain stresses steady care to keep something unchanged, as with houses. Sustain stresses keeping something alive under pressure or scarce resources, as with crops or economies. Maintain can also mean insisting something is true; not compared.

这两个词在这个义项上都表示“维持、使继续保持某种状态”，但maintain更强调通过持续的照料或努力使事物保持良好状态或不变，常用于房屋、设备、标准、关系等；sustain更强调在压力、困难或资源有限的情况下使某事物得以延续，常用于农作物、生命、经济等。这里不比较maintain的“主张，坚持（观点）”这一义项。

Compared meaning: to help keep something going (verb).

比较义项：给予帮助以维持某事物的存续或正常运转（动词）。

• support

  A general word for giving help, encouragement, or resources to someone or something, often used for people helping each other; not tied to duration.

  泛指给予帮助、鼓励或资源，常用于人与人之间互相帮助，不强调持续时间的长短。

  Friends should support each other during difficult times.

  朋友之间在困难时期应该互相扶持。

• sustain 本词

  Emphasizes keeping something alive, functioning, or in existence over a period of time, often through continuous effort; more formal, typically used with crops, life, or systems.

  强调通过持续的努力使某事物在一段时间内维持存活或正常运转，语气更正式，常与庄稼、生命、体系等词搭配。

  Farmers work hard to sustain their crops during dry seasons.

  农民们在旱季努力工作以维持庄稼的存活。

Support and sustain both mean to help something continue to exist or work well. Support is a general word for giving help of any kind, emotional, physical, or financial. Sustain stresses keeping something alive or working over a long time, and sounds more formal.

两者都表示“给予帮助使某物得以维持”，但support泛指各种形式的帮助（情感、经济、身体等），常用于人与人之间；sustain更强调长期、持续地维持某种状态或使某物存活下去，语气也更正式，常搭配资源、生命、经济等词。这里不比较support的“证实、证明”等其他义项。