I don't know what we will do this afternoon改为同义句I don't know _ _ _ this afternoon

I don't know what we will do this afternoon改为同义句I don't know _ _ _ this afternoon
I don't know what we will do this afternoon改为同义句
I don't know _ _ _ this afternoon

I don't know what we will do this afternoon改为同义句I don't know _ _ _ this afternoon
what to do
不定式可表将来时

I don't know what_ to_ _do this afternoon