Peter has a swimming pool .It _________ long.
Mr Green is our new teacher this term. He teaches _____ history.
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.