10 He often asks me the question ___ the work was worth doing.A if B whether C that D when
The question ______ last night was of great importance.
I heard a soft _______ at the door. When I looked up, I found it was Mary.
Last night he left his bike outside and had it_______.
To keep ______, we must do more out-of-door exercises.
Thank you for_______ my trouble.