Indirect questions

[sunny1]

Please could you help me understand the following.

Suppose you have an indirect question, like "I never knew who was coming" or "I wasn't sure whom they saw". In those examples the relative pronoun takes its case from the main clause, i.e. it is the object of the verb in that clause.

But what if you had simply "I never knew who" or "I wasn't sure who". In those examples there isn't additional context to help determine the case of the relative pronoun.

Does it function as a complement? Is it necessarily an object? If so, absent further context, should it be "I never knew whom" or "I wasn't sure whom"? Because in these sentences there is an ambiguity to me. They could be subject - verb - object sentences or they could be indirect questions.

Many thanks.

[Minoo]

Interesting question! 

This problem doesn't arise in British English because we don't use 'whom' except when it's right next to a preposition. So, regardless of the case, in British English, you would use 'who'.

I can't be sure in American English, but my guess is that they would use 'who' as well if there were some ambiguity.

[sunny1]

Terrific, thank you very much Minoo.