Used to express gratitude or relief.
An exclamation used to express pleasant or unpleasant mild surprise, indignation, or impatience.
For which cause, reason, or purpose.
The cause, reason, or purpose for which.
Introducing a noun or other phrase.
Introducing a verb phrase (bare infinitive clause).
Introducing a complete question.
With a negative, used rhetorically to make a suggestion.
Reason.