A:AB=CD
B:EC=BF
C:∠A=∠D
D:AB=BC
下图漫画告诉我们要( )
l1:2x+y﹣1=0,l2:y=kx﹣5,l1⊥l2的充要条件( )
如果转动200次,估计指针落在蓝色区域有多少次呢?
Sam is clever, and he's ____( also / too) hard-working.