John wants to be a , so he often helps sick people in the hospital.
The boy has a cold and the doctor asks him ________ more water.
—Oh, you look tired. Why? —I ________ to the Great Wall yesterday. It was really wonderful.
Ben is one of ________ students in our class. He keeps doing sports every day.
Mr. Wang _______ dinner with his family now. They look very happy.
I knocked on the door but ________ answered.