Around 15,000 officials gathered in Copenhagen, trying to map out an effective strategy _____ the battle against climate change.
He had ______ in finding Mr. Green’s house.
——Who telephoned just now? ——Sorry. I couldn’t ______ the voice.
Only when ______ in 1918, ______ happily back to work.
The boy would have died, _______ on him without delay.
Do you mind ______ how you succeed?