How to draw a border for multiple graphs in one pager

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My
question is How do I remove the outside frame. It seems that Box() can
only generate four sided boders. Or is there any way that I can draw
the inner border without using box().

Try using box only on the second and third plot:

pie(value,labels=lbls,col=colors,radius=0.5)
pie(value,labels=lbls,col=colors,radius=0.5)
box(which="figure",type="l")
pie(value,labels=lbls,col=colors,radius=0.5)
box(which="figure",type="7")
pie(value,labels=lbls,col=colors,radius=0.5)

Another question is how
can I align the text in the legend? You can see when I concatenate the
concentration level and the percentage, it looks unclear. Is it
possible that percentage can be right aligned?

I think if you want left-aligned labels and right-aligned percentages, 
you will have to do the best you can with different numbers of spaces 
between the labels and percentages.

Jim