A:①④
B:②③
C:③④
D:①②
命题“∀x∈R,x2+2x+2>0”的否定是( )
3.8×2=____10×0.7=____13.9×0=____5.5×1=____2.5×4=____ 2.5×8=____0.5×0.2=____3.2×3=____