Student or Learner
Which is the correct preposition after necessary?
This tool is necessary in/for repairing it.
You need this tool to repair it.
This tool is needed to repair it.
This tool is necessary for the repair.
I would not say This tool is necessary [any] repairing it.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.