←概率论 ∑Xk-E(∑X)∑Xk-∑k k=1 B D(∑X) 的分布函数Fn(x)对于任意x,满足 iF(x)=imPk-∑ k k=1 n→0 n→0 B dt=Φ(x) 2兀概率论 n n k k n k k n k k n k k n k k n B X D X X E X Z  −  =   −  = = = = = = 1 1 1 1 1 ( ) ( )  的分布函数Fn (x)对于任意x，满足             −  = = = → → x B X F x P n n k n k k k n n n 1 1 lim ( ) lim  =   x - -t 2 e dt 2 1 2  = (x)