Dear N:

You wrote:
> Is this sentence correct:
>
> 1-She was waiting for the man to repair the heating system to arrive.
> (The man’s job is repairing heating systems.)

No. You have misplaced modifier. It needs to read, “She was waiting for the man to arrive to repair the heating system.” The second infinitive phrase is adverbial and is more or less equivalent to “in order to repair.” If you
want to emphasize the work that the man does, you would refer him as a “repairman” or “heating system repair man.”
>
> 2-He is the man to drive us there tomorrow.
> Does this sentence mean:
> A-that he is the man who CAN drive us there tomorrow
> or:
> B-He is the man who has been given the job of driving us there tomorrow
> or:
> C-He is the man who WILL drive us there tomorrow
>

When we say someone is THE person TO do something, it is really idiomatic and means, “he is meant to” or “he is the best person to.” So you would be saying. “He is the best person (or the only person meant) to drive us there
tomorrow.”

> 3-He is the man to save the company.
> Does this sentence mean:
> A-He can save the company
> or
> B-He will save the company
> or
> C-He has been assigned to the task of saving the company
>
Again, see above. It closest to A but with emphasis–“He is the only one who can save the company” or “He is meant to save the company” or “He is the best person to save the company.” As you can see, this is a very emphatic
idiom.

[We note that questions concerning the use of articles in English come from people whose native language does not have articles or does not distinguish between definite and indefinite articles. This can be tricky for such people to grasp how articles are used in English. We hope this posting and others like it can help clarify this difficulty.]