--- Are these your books? --- ________.
We must protect (保护) animals like elephants, because they’re _____.
There are _____ teachers in our school.
When we go to the library, we must be _____ in the library.
What is time? Time is the seconds, _____, hours, days, years shown(显示) in our watches and calendars.
—Can Mary _____ English?—Yes, and she can sing many English songs.