Question: how can i draw many points relating x axis in a same coordinate?

i got many float data from 'for' sentence relating x,e.g.

for i to 4 do
  x := 0.01*i;
  if (i = 1) then
    y := 0.2;
    z := 0.05:
  elif (i = 2) then
    y := 0.3;
    z := 0.5:
  elif (i = 3) then
    y := 0.5;
    z := 1.05:
  elif (i = 4) then
    y := 1.2;
    z := 2.05:
  end if;
end do;

i got the values of y and z relating x four times in this loop,(x&y:[0.01,0.2],[0.02,0.3],[0.03,0.5],[0.04,1.2] and x&z:[0.01,0.05],[0.02,0.5],[0.03,1.05],[0.04,2.05]).
so,i want to draw the points by two lines relating x axis (x=0.01..0.04) in a same coordinate.

i knew how to draw a point in a coordinate,like this
but ,how can i continuously draw the points by plot method,furthermore draw the points by two lines about y and z (of course by two colors).if u hv some gud idea,please tell me,thank u!

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