Meaning & use
heaven knows
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Meanings
phrasefixed phraseinformal
Used to say that you do not know something at all.
Grammar: Often followed by a clause beginning with 'why', 'what', 'how', etc. It can stand alone as a response.
Patterns
- heaven knows why/what/how ...
- heaven knows
Heaven knows why she left so early.
Heaven knows what he was thinking when he bought that car.
Heaven knows how we'll finish this by Friday.
phrasefixed phraseinformal
Used to emphasize that a statement is definitely true.
Grammar: Often used with 'is' or 'are' to stress a fact.
Patterns
- heaven knows (that) ...
- heaven knows + clause
Heaven knows I've tried to help him.
Heaven knows it's not easy to find a good job these days.
Heaven knows she deserves a break.
Common combinations
- heaven knows why
- Heaven knows why they decided to cancel the trip.
- heaven knows what
- Heaven knows what she sees in him.
- heaven knows how
- Heaven knows how they managed to survive.
- heaven knows I've tried
- Heaven knows I've tried to be patient with him.
Synonyms and how they differ
- God knows
- Same meaning and use, but may sound stronger or more religious to some people.
- who knows
- Similar informal way to say you don't know, but less emphatic and can stand alone more easily.
Practice
Choose the correct completion: 'Heaven knows ___ she sees in that awful man.'
Choose one answer.
'What' is correct because it introduces the thing she sees. 'Which' would need a limited set of choices, 'who' would refer to a person as the object, and 'whose' shows possession, none of which fit here.
Make it your own
Write a sentence using “heaven knows”, then check it and compare it with the examples above.