who'd
pron.pron. a short way of saying 'who would' or 'who had'. You use it in speaking or casual writing to save time.
pron. a contraction of the relative or interrogative pronoun 'who' combined with the auxiliary verbs 'would' or 'had'.
Who'd like some more coffee?
The police are looking for a witness who'd seen the car leaving the scene before the sirens started.
In a room full of experts, it was the youngest intern who'd eventually propose the solution that saved the entire project from certain failure.
Functions as a contraction; the following verb form determines if it represents 'would' (base form) or 'had' (past participle).
Who'd of thought it?Who'd have thought it?Learners often write 'of' because it sounds like the weak pronunciation of 'have' in contractions.