—______is your birthday gift, Linda?
— It's a circle.
A:What kind
B:What color
C:What time
D:What shape
如图所示,在△ABC中,∠C=90°,AC=6cm,BC=8cm,点P从点A出发沿边AC向点C以1cm/s的速度移动,点Q从C点出发沿CB边向点B以2cm/s的速度移动.