右图所示是a、b、c(不含结晶水)三种固体物质的溶解度曲线，下列说法正确的是(         )

下列物质被俗称为干冰的是（　　）

B

    Kate is an English girl. She lives in a tall building in the city of London. There are sixteen floors in the building, and she lives on the tenth floor. She uses a lift(电梯) to go up and down.

    Kate studies in a middle school near her house and she works hard. She goes to school early. Every day she leaves her home at half past six. She walks to the lift, and it takes her down to the first floor.

    There is a bus stop near the building. Usually she takes the No. 7 bus to her school. Classes begin at eight. She goes to play games at three forty. She gets home at a quarter past five. She begins to do her homework at eight and finishes it at half past nine.