We're tired because we have ________ yin.
We visited Beijing University _______ the first day of our trip.
_______ is necessary for us _______ our own dreams.
--Who is the man over there? Is it Mr. Li ?--No, it _______ be him. Mr. Li is much taller.
What will the weather _______?
_______the population of China?_______over 1,300,000,000.