A
This is the house in which he lives.
This is the house he lives in.
To what are you referring?
What are you referring to?
This is the person to whom I gave the book.
This is the person I gave the book to.
On what surface did you put the glass?
What surface did you put the glass on?
This is the issue about which we are most concerned.
This is the issue we are most concerned about.
Where is the place in which we are supposed to meet?
Where is the place we are supposed to meet in?
What is the subject about which you are worried?
What is the subject you are worried about?
This is the project upon which the team is focused.
This is the project the team is focused upon.
This is the difficulty through which we must pass.
This is the difficulty we must pass through.
That is the goal toward which we are working.
The company with which he signed the contract is a startup.
The company he signed the contract with is a startup.
This is the hypothesis for which the scientist found no evidence.
This is the hypothesis the scientist found no evidence for.
This is the policy against which the public protested.
This is the policy the public protested against.
This is the framework within which we can operate.
This is the framework we can operate within.
This is the challenge through which we must innovate.
This is the challenge we must innovate through.
The theory about which the scientific community is divided is controversial.
The theory the scientific community is divided about is controversial.