缓解资源稀缺的途径有哪些？
参考答案：
①充分发挥技术进步的作用；
②加大经济的开放度；
③改善交通运输条件；
④有效的制度安排和价格政策。
Wang kun : Have you looked at a map?
Wang wei : What did you say just now?
Wang kun : I asked you ______________.
A．whether you have looked at a map
B．whether you had looked at a map
C．whether have you looked at a map
D．whether had you looked at a map
放射性活度与放射性浓度。
