Chinese people have been using paper for over______ years.

Have you ever seen a panda , Linda?—Yes , I just saw _________at the zoo last Sunday .

Is your grandma still ________?—Of course. She __________ with my aunt in the countryside.

We are _________ by doctors to eat more natural food and take plenty of physical exercise.

You might as well expect a river to flow backward ____ us carrying out the plan.