---Many species are now in danger of dying out.----True.Measures should be______to protect them right now.
Alice received an invitation from her boss, ________ came as a surprise.
Most people find it hard to ________Beijing Opera to foreigners because of cultural differences.
At the age of fifteen she gave up taking piano lessons to _____ her school work.
It is still under discussion _________ the old bus station should be replaced with a modern hotel or not.
David is a skillful worker. I’m sure he has enough _______ to fix all the electronic ______.