The number of people invited _____fifty, but a number of them ______ absent (缺席) for different reasons.
Mr. Black used to be busy. But now he’s retired and , so he has plenty of time to exer cise.
My grandpa is going to be years old this year. He will have his birthday party this Saturday evening.
—Will you get there by ________bike? —No, I will take ________bus.
The young has over twenty .
I used to swim ____ the Yellow River when I was young.