已知命题 $p:\exists n\in N,2^n>1000$,则 $\neg p$为(   )

A．	$\forall n\in N,2^n\le 1000$	B．	$\forall n\in N,2^n>1000$
C．	$\exists n\in N,2^n\le 1000$	D．	$\exists n\in N,2^n<1000$