如果水蒸气被加热到高于沸点温度，该蒸汽称为（）蒸汽。
A.饱和
B.过热
C.低压
D.中压
参考答案：B
锅炉水位不明，如何判断？
A first-grade teacher use ten flash cards, numbered 1 through 10, to teach her students to order numbers correctly. She has students choose four flash cards randomly, then arrange the cards in ascending order. One day, she removes the cards numbered "2" and "4" from the deck of flash cards. On that day, how many different correct arrangements of four randomly selected cards are possible
A．70
B．210
C．336
D．840
E．(E) 1,680
