.show( [duration ] [, complete ] )
duration (default: 400)
Type: Number or String
A string or number determining how long the animation will run.
complete
Type: Function()
A function to call once the animation is complete, called once per matched element.
看下源码哦,$.fn.show:
可以看到不传speed直接就显示(改css)啦,传入0才会走整个animate的机制,并没有把speed默认为0哦。