某扇形的面积为12πcm2,圆心角为120°,则该扇形的半径是( )
A:3cm
B:4cm
C:5cm
D:6cm
十亿零五十万零二十八写作____,它是一个____位数,最高位的计数单位是____.
已知直线l1:2ax+(a+1)y+1=0,l2:(a+1)x+(a﹣1)y=0,若l1⊥l2,则a=( )
— I'll be away on a business trip. Would you mind looking after my cat?
— Not at all. ________________.