The first/last/next/only to V or Ving

Question

Recently, I'm quite confused about the usage of the first(second,third……)/next/last/only.

He was the first ____ the school in that area.

(A)to open (B) opening

The answer is (A).

But,I remember the first(second,third……)/next/last/only can be used with the relative pronoun "that".

For example,he was the first person "that" opened the school in that area.

Also,I remember relative pronoun can be deleted with the verb it brings turning into ving or vpp.

Therefore,in my mind,the sentence"He was the first opening the school in that area" can make sense.

So,what do you think?and why？or is it just an idiom？

Answer 1

{combined my comments into an answer: xDD}

"He was the first person opening ..." is fine, but if you omit 'person' and expect 'first' to act as a pronoun, you create a garden path because 'the first opening' looks like a noun phrase (!"He was the first opening").

Yes, you can use a relative pronoun and say "He was the first that opened ..." or "He was the first that was opening ...", but English does prefer using 'who' when relativising a person. Using 'that' or 'which' has an advantage in that we use 'that' for restrictions and 'which' for adjuncts. With 'who' this distinction is entirely dependent on whether a comma (pause) is used before the relative pronoun.

To reiterate, 'First' can be used like a [pro]noun, and its antecedent can be a person, but 'first' can also be an adjective, and any v-ing can be a noun (gerund), so the parse gets confusing: ("She was the first arriving"). One fix is to insert another [pro]noun: "She was the first one arriving", "He was the first one opening ..."