∵a-b=5,ab=-2,
∴1a-1b=b-aab=-a-bab=-5-2=52.
故答案为:52
–________ you turn down your radio, please? –Yes, I can.
A.May
B.Need
C.Must
D.Can
入某换热器前循环水管,管径d=100毫米,管中流速V=1.0米/秒,水温为20℃,水的运动粘度r=0.0101厘米2/秒,试判别管中水流处于何种流态?