請問如何抉擇以分詞片語或是不定詞片語來當句子中的形容詞較適合呢?

Igor Sikorsky was the first person to develop a modern helicopter. (O)
= Igor Sikorsky was the first person who developed a modern helicopter.

Igor Sikorsky was the FIRST person DEVELOPING a modern helicopter. (X)

其實這是英語句型的問題，不要被文法書上的分詞片語、不定詞片語把你導向文法分析。英文句型 the first ～ to ～ 是很普遍的。

如果一定要用英文法來解說，那可以記住這句話：「英文關係子句前面的名詞有最高級或序數： the first、 the next、the last 等限定時，後面的關係子句可以簡化成不定詞片語」。例如：

Maria Mayer is the last woman to win a Nobel Prize in Physics.

Paul Sturgess is the tallest man to ever play pro basketball.

在非常特殊的情況下，可以看到 the first person 後面有 ~ing 的片語，但通常那不是分詞，而是形容詞，例如：

He is the first person willing to help me.

這裡 willing 不是分詞，是形容詞「有意願的」，剛好有 ～ing 的形式而已。

Igor Sikorsky who was the first person to invent the modern helicopter. Yip

For the past participle(=participial):- -ed ; developed
---has developed;---used after the main verb--verb to be---"was" in time sequence of the sentence
----Error and correction:-eg:-Ignore Silorsky was the first person who has developed or(=to have developed) a modern helicoper.Since present participle "developing" is in-admissible, cannot be allowed or accepted here.
For infinitive:-an infinitive is used by itself.develop in "to develop"--to develop a modern helicopter
----He "can develop" a modern helicopter.
---This use is called the bare infinitive with which you can't use here; Hence the to-infinitive used as in
---Ignore Sikorsky was the first person "to develop" a modern helicopter,(correct)