It's not proper for kids to have too much pocket money because they may buy ______.
A:something necessary
B:necessary anything
C:something unnecessary
D:unnecessary something
如图所示的圣诞帽呈圆锥形,其母线长为2,底面半径为1,则它的侧面积为
①如果碰到正闲游的同伴,它们就会打起来。
②这些小虾,有的通体透明,像玻璃似地;有的稍微带点灰黑色,甚至背上、尾巴上还积着泥,大家叫它千年虾。