exactly

Compared meaning: exactly, with no difference or error (adverb).

比较义项：确切地，精确地（副词）。

• exactly 本词

  The most general and neutral of the three; used freely before numbers, times, places, and questions, and often stands alone to agree ('Exactly!').

  三者中最通用、最中性的词，可自由用在数字、时间、地点或疑问句前，也常单独用来表示赞同（“Exactly！”，意为“没错！”）。

  I don't know exactly how much it costs.

  我不知道确切的价格是多少。

• just

  Limited to a handful of fixed phrases such as 'just right' or 'just what I needed'; more casual in tone; its far more common sense is 'a moment ago', not compared here.

  只用于少数固定搭配，如“just right”（恰到好处）或“just what I needed”（正是我需要的），语气更口语化；它更常见的义项是“刚刚，才”，这里不作比较。

  This soup is just right, not too hot and not too cold.

  这碗汤正好合适，不太烫也不太凉。

• precisely

  More formal and technical, common with measurements or times, and can stand alone as a more formal agreement than 'Exactly!'.

  语气更正式、更专业，常用于测量或时间等场合，也可单独使用，作为比“Exactly！”更正式的赞同用语。

  The measurements must be precisely correct, or the machine won't fit together.

  测量数据必须精确无误，否则机器就装不到一起。

Exactly, just, and precisely mean 'with complete accuracy' but differ in formality: exactly is the most general, used before numbers, times, or questions; precisely is more formal, common with measurements; just appears in phrases like 'just right' (its meaning 'a moment ago' is not compared).

这三个词在“确切地、精确地”这一意义上很接近，但正式程度和用法范围不同：exactly最通用，precisely更正式、更书面，just只用于少数固定搭配（如“just right”），语气随意，且更常表示“刚刚，才”之意。这里不比较just的“刚刚，才”这一时间义项。