如图,已知∠ACB=90°,AC=BC,BE⊥CE,AD⊥CE于点D,AD=2.5 cm,DE=1.7 cm,则BE=( )
A:1 cm
B:0.8 cm
C:4.2 cm
D:1.5 cm
Not having worked out the program, ________ leave the office.
多项式(a﹣2)m2+(2b+1)mn﹣m+n﹣7是关于m,n的多项式,若该多项式不含二次项,求3a+2b.