采用弹性分析方法处理经济问题的优点有( )。
A.简单易行
B.需要数据少,计算方便
C.计算成本低
D.应用灵活广泛
E.短、中长期预测均适用
参考答案:A,B,C,E
Hardly __________ the Shanghai Expo _________ we realized we forgot our ID cards in the room.
A.we had got to ; that
B.we got to ; when
C.had we got to ; when
D.had we got to ;than
减压塔的抽真空系统冷凝器排液管高度至少应有()m。
A.5
B.10
C.15
D.20