If you have ________new message on it, please call me.
A:any
B:some
C:lots
D:lot
如图,在直角三角形ABC中,∠C=90°,AB=10,AC=8,点E、F分别为AC和AB的中点,则EF=( ).
一凸透镜的焦距是8cm,将点燃的蜡烛放在离凸透镜15cm处,则所成的像是( )