Question

he wanted to know if he......attend the show (will /may/could)

Answer 1

if he will attend the show

Answer 2

'He wanted to know if he could attend the show.'

• 'Could' is an example of a modal auxiliary verb which represents the ability or intent of an action to be performed.
• Along with the main verb (attend), it presents the possibility or necessity of the action. In the above sentence, 'could' means the permission to commit the action of attending the show.