单项选择题
Conversation One
A. Africans are not very brave and resourceful. B. There is no treatment or healthcare center at all. C. There were no effective prevention systems. D. There was no formal education in Africa at all.
A. He must take a connected flight at Jacksonville. B. He has to change the flight at Albany. C. He will fly for two hours. D. He will fly directly to his destination.
A. They don’t need conventional signs and symbols. B. They only require a receiver in communication. C. The distance between communicators can’t be too long. D. They are not restricted in time and space.