题目

So far this year we________ a fall in house prices by between 5 percent and 10 percent. A . saw B . see C . had seen D . have seen 答案：D四口之家分别单独使用不同种类的燃料时，平均月消耗量分别为：木柴约200 kg、烟煤约80 kg、液化石油气约30 kg、煤气约60 kg。这四种燃料中，哪一种燃料的热值最高( )A. 木柴 B. 烟煤 C. 液化石油气 D. 煤气