TOEFL Listening: TPO-TOEFL听力TPO - Q06ATN8Z0_ETB4T5R$

Why does the professor mention the writer Arthur C. Clarke? A. To use a comment made by Clarke as a way of answering a student's question B. To familiarize students with Clarke's ideas on space engjneering C. To cite a prominent opponent of the idea of space elevators D. To point out that Clarke wrote about carbon nanotube technology long before it became a reality