如图为实验室制取少量乙酸乙酯的装置图.下列关于该实验的叙述中,不正确的是( )
下面是四位同学凭想象描写南极地区的语句,你认为正确的是( )
设随机变量X~N(2,4),则D(12X)的值等于( )
“One tree can't make a forest” tells us no one would be heroes ____ (with) his friends.