题目内容：
The author’s purpose in presenting the first paragraph is__________．
A．to explain the background and new features of today’s astronomy B．to discuss in detail the most recent achievements in space research
C．to introduce some newly established space stations
D．to illustrate that the world today is different in many aspects from that of a genera—tions ago
参考答案：【答案仅供学习，请勿对照自行用药等】
答案解析：