2x2-8=( )
2(x-1)(x+2)
The preschool children who watch TV programs with violent scenes are more likely to have sleep problems than those who watched programs for the age.
A.accurate
B.fantastic
C.delicate
D.appropriate
在-9、+1.6、10、0、-4.5、+1000、-6这些数中,正数有______,负数有______.