种子萌发所需的外界条件是( )
①适量的水分 ②充足的光照 ③适宜的温度 ④丰富的养料 ⑤充足的空气.
A:①②③
B:①③⑤
C:①②③④
D:①②③④⑤
已知随机变量ζ服从正态分布N2,σ2,且Pξ<4=0.8,则P0<ξ<2=( )
—I hope that what we have said will not fall on deaf ears.
— Don’t worry. It’s good for their study. They will follow it.