My bike is lost. I can’t find _______. So I want to buy a new _________.
Water is very dangerous sometimes. So we must be careful _____ it.
In our city, _____ middle school students want to be a teacher in the future(将来) every year.
My brother is _____ his homework. He often _____ his homework at home.
—Here is a schoolbag. Whose is it? —Oh, it’s _______ Thank you.
—_______ is this pen? —It’s mine.