[R] how to ajust y-axis values in plot() ?

[PO SU]

Dear helpeRs,
  I want to plot( 11:20 ) in a plot.
 if i just type the code above, the y value  will be from 11 to 20, now i want the value from a given range like  0 to 40, how can i do it? 
I read ?plot  for a while but  still can't solve it. 
Actually, the qustion is founded when i already plot a plot like plot(11:20) , but when i abline(h=40), i found it will go out of the plot even after i used abline(h=40,xpd=T).
SO, may you help me?





--

PO SU
mail: desolator88 at 163.com 
Majored in Statistics from SJTU