A precursor is something that came before, and that helped the later thing become what it is. An old steam engine can be a precursor of the modern train; a mild tremor can be a precursor of a bigger earthquake.

A precursor is something that came before「precursor」指某個先出現的東西, and that helped the later thing become what it is而且幫助了後來的東西變成現在的樣子。An old steam engine can be a precursor of the modern train一台舊蒸汽引擎可以是現代火車的 precursor（前身）; a mild tremor can be a precursor of a bigger earthquake一次輕微的地震可以是更大地震的 precursor（前兆）。

In science, a precursor is a substance the body or a factory uses to make another substance.

In science在科學上, a precursor is a substancePrecursor 指一種物質 the body or a factory uses to make another substance身體或工廠會用它來製造另一種物質。

The word carries a feeling of “this opened the door.” Though actually, it is not just “the previous one.” A predecessor is often the person who had your job before you. A precursor is more about influence and development, and it is used as much for things, ideas, and chemicals as for people.

The word carries a feeling of這個字帶有一種感覺 'this opened the door'「這東西打開了門」。Though actually不過其實, it is not just 'the previous one'它不只是「前一個」的意思: a predecessor is often the person who had your job before youpredecessor（前任）通常是指之前做你這份工作的人。A precursor is more about influence and developmentPrecursor 比較著重在影響和發展, and it is used as much for things, ideas, and chemicals as for people用在事物、想法、化學物質上，跟用在人身上一樣多。

It is a formal, slightly academic word. In everyday talk, people say “that came first” or “that led to…”

It is a formal, slightly academic word這是個正式、有點學術味的詞。In everyday talk在日常對話裡, people say 'that came first'大家會說「那個先出現」 or 'that led to…'或「那個導致了…」。