丝绸之路指历史上陆续形成的、遍及欧亚大陆甚至包括北非和东非在内的（）线路的总称。
A、旅游
B、长途商业贸易
C、文化交流
D、运输
参考答案：B, C
With the development of the central and western China，more and more modem cities have
——in what was a wasteland ten years ago
A．built-up
B．sprung up
C．grown up
D．risen up
朱砂与磁石的功效应用有何异同？
