汽耗率
参考答案：
机组每发一千瓦时电量所消耗的蒸汽量。
The first lady of the USA, Michelle Obama visited China this spring. She with her mother and two daughters China for a week.
A．stayed in
B．has been in
C．has been to
D．has gone to
当巴西出现灾害性天气时，国际期货市场上的咖啡和可可的价格（）。
A.下跌
B.上涨
C.不变
D.不一定
