مَاذَا؟

He writes a letter; to compose a written message.

I ask; to put a question to someone.

Which?

Which?; asking for a choice from a definite set.

He answers; to give a response.

Why?; for what reason or purpose.

Welcome (response to 'marhaban' or 'ahlan wa sahlan')

Speaking, talk

A talk, especially an informal one, between two or more people.

Phone.