单项选择题A. They were both waiting in line for a film. B. Both of them were fans of a play writer.C. They both favored their work. D. They were selling tickets at the same time.
单项选择题A. The birds can fly upward to the air. B. The birds are able to use the upward airstream. C. The birds can create airstream using their wingtips. D. The birds more rely on the front leading birds.