用铝热剂冶炼难熔金属，是因为铝是[ ]
A．具有导电性
B．具有延展性
C．既能与酸反应又能与碱反应
D．被氧化过程中放出大量的热
答案：D
下列光学设备中，应用的原理与如图所示的凸透镜成像规律相同的是
A．照相机
B．老花镜
C．幻灯机
D．放大镜
When we got to the cinema, _____ a queue outside. _____ a very long queue, so we decided not to wait there. [ ]
A. there is; It is
B. there was; It was
C. it was; There was
D. there is; It is
