When _____ about one of the biggest concerns today, many people mention the sharp rise in prices. [ ]

A. asking

B. to ask

C. having asked

D. asked

下列事件按先后排序正确的是：

①中国人民基本解决了温饱问题 ②轮船开始进入中国

③丹麦的电报公司在上海建立第一个电报机房 ④同盟会的机关刊物《民报》创刊 [ ]

A．①②③④

B．②④③①

C．②③④①

D．③②④①