A:not until midnight did he go
B:until midnight that he didn’t go
C:not until midnight that he went
D:until midnight when he didn’t go
抛物线y2=2pxp>0的焦点为F,已知点A,B为抛物线上的两个动点,且满足∠AFB=120°.过弦AB的中点M作抛物线准线的垂线MN,垂足为N,则MNAB的最大值为 ( )
如图,在平行四边形ABCD中,E是CD的中点,AD、BE的延长线交于点F,DF=3,DE=2,则平行四边形ABCD的周长为( )
求: