This shows:
<ul>
<li>
Append
<li>
ParametricPlot  for Log-Log plots
<li>
DisplayFunction->Identity
<li>
DisplayFunction->$DisplayFunction
<li>
Working with Table, List, Flatten 
</ul>
<listing>
fff[x_] = 10-1.8/x
ggg[x_] = 8-0.2/x

Pl[1]=ParametricPlot[{{Log[10,x], Log[10,fff[x]]},
{Log[10,x], Log[10,ggg[x]]}}, {x, 0.2, 10},{Ticks -> None},
{Frame-> True},DisplayFunction->Identity]

fff[x_] = 0.3 (11-1.1/x)
ggg[x_] = 8-0.4/x

Pl[2]=ParametricPlot[{{Log[10,x], Log[10,fff[x]]},
{Log[10,x], Log[10,ggg[x]]}}, {x, 0.2, 10},{Ticks -> None},
{Frame -> True},DisplayFunction->Identity]

gr={};For[i=1,i<3,i=i+1, gr = Append[gr, Pl[i]] ]
 Show[gr,DisplayFunction->$DisplayFunction]

</listing>

Here are several copies of use of Table and Flatten etc....

<listing>
(*Defining Several plots and numbering them 
as Pl[i]    Then combine them into one gr *)

fff[x_] = 10-1.8/x
ggg[x_] = 8-0.2/x
Pl[1]=ParametricPlot[{{Log[10,x], Log[10,fff[x]]},
{Log[10,x], Log[10,ggg[x]]}}, {x, 0.2, 10},{Ticks -> None},
{Framed -> True}]
fff[x_] = 11-1.1/x
ggg[x_] = 8-0.4/x

Pl[2]=ParametricPlot[{{Log[10,x], Log[10,fff[x]]},
{Log[10,x], Log[10,ggg[x]]}}, {x, 0.2, 10},{Ticks -> None},
{Framed -> True}]

gr={};For[i=1,i<3,i=i+1, gr = Append[gr, Pl[i]] ]
 Show[gr]
(*
Defining Several Functions as functions of an index
Making Plots for each of them 
and numbering them 
as PPl[i]    Then combine them into one gr *)

Curv[n_,x_] = 10-0.1 n/x
BCurv[n_,x_] = 8-0.2 n/x

For[i=1,i<4,i=i+1, 
PPl [i]=ParametricPlot[{{Log[10,x], Log[10,Curv[i,x]]},
{Log[10,x], Log[10,BCurv[i,x]]}}, {x, 0.2, 10},{Ticks -> None},
{Framed -> True}] ]    (* For Loop done *)
gr={};For[i=1,i<4,i=i+1, gr = Append[gr, PPl[i]] ]
 Show[gr]

(*
Defining Several Functions as functions of an index
Defining Plots for each of them 
and numbering them 
as PPPl[i]    Then combine them into one gr
*)

Curv[n_,x_] = 10-0.1 n/x
BCurv[n_,x_] = 8-0.2 n/x
PPPl [i_]:=ParametricPlot[{{Log[10,x], Log[10,Curv[i,x]]},
{Log[10,x], Log[10,BCurv[i,x]]}}, {x, 0.2, 10},{Ticks -> None},
{Framed -> True}] 
gr={};For[i=1,i<4,i=i+1, gr = Append[gr, PPPl[i]] ]

Show[gr]

(*
Defining Several Functions as before
USING TABLE    (Following the Book)     *)

Curv[n_,x_] = 10-0.1 n/x
BCurv[n_,x_]= 8-0.2 n/x

Pl1=Plot[Release[Table[ Curv[n,x],{n,4}] ],{x, 0.2, 10}];
Pl2=Plot[Release[Table[ BCurv[n,x],{n,4}] ],{x, 0.2, 10}];
Show[Pl1,Pl2]


Plot[Release[Table[ Curv[n,x],{n,4}]],{x, 0.2, 10}]
(*
COMBINING TABLES
USING FLATTEN     *)

Curv[n_,x_] := 10-0.1 n/x;
BCurv[n_,x_]= 8-0.2 n/x;

Hlist={Table[ BCurv[n,x],{n,4}]};
Hlist=Append[ Hlist,Table[ Curv[n,x],{n,4}] ];
Hlist = Flatten [Hlist] ;
Plot[Release[Hlist ],{x, 0.2, 10}]



Curv[n_,x_] = 10-0.1 n/x 

Print[Table[ Curv[n,x],{n,1,4} ]]

      0.1       0.2       0.3       0.4
{10 - ---, 10 - ---, 10 - ---, 10 - ---}
       x         x         x         x

Plot[Release[Table[ Curv[n,x],{n,4}] ],{x, 0.2, 10}]

(*
SHOWING that one can REdefine  one of the functions
by hand    *)

Curv[1,x_] := x;Hlist={Table[ BCurv[n,x],{n,4}]};
Hlist=Append[ Hlist,Table[ Curv[n,x],{n,4}] ];
Hlist = Flatten [Hlist] ;
Plot[Release[Hlist ],{x, 0.2, 10}]



</listing>