用所给动词的适当形式填空
Look, there are so many people over there. What ____(happen)?
It's seven in the morning. It's time for us ____ (go) to school.
Look at the clouds in the sky. I think it____(rain).
____ (be) everyone here? Yes, Let's____ (start) now.
He ____(be) be fifty years old next month. But he ____ (look) so young.
Teachers' Day____(come) . And we ____ (plan) to buy some flowers for Mrs. Li.
My mother usually ____(shop) for food on Sundays.
为等比数列，且
=" " （ ）