God knows

Từ điển Oxford Advanced Learner 8th

God/goodness/Heaven knows idiom
(informal)
1. used to emphasize that you do not know sth
• God knows what else they might find.
• ‘Where are they?’ ‘Goodness knows.’  Some people may find the use of God knows offensive.
2. used to emphasize the truth of what you are saying
• She ought to pass the exam— goodness knows she's been working hard enough.
Main entry: ↑know_idiom