how can i add more multiple curves

syms m h v0 alpha alp time x(t) y(t) t xn xn2;
m=input('Nhap m: ');
h=input('Nhap h: ');
v0=input('Nhap v0: ');
time=input('Nhap time: ');
dvgoc=input('Chon don vi goc (1:rad, 2:deg): ');
if (dvgoc==1)
    alpha=input('Nhap goc nem (Rad): ');
elseif (dvgoc==2)
     alpha=input('Nhap goc nem (Deg): '); 
     alpha=alpha*pi/180; 
elseif (dvgoc==2)
end
Dx=diff(x);
D2x=diff(x,2);
x(t)=dsolve(m*diff(D2x)==-h*diff(Dx),x(0)==0,Dx(0)==v0*cos(alpha),D2x(0)==0);
disp('x(t)=');
pretty(x(t));
disp(x(t));
Dy=diff(y);
D2y=diff(y,2);
y(t)=dsolve(m*diff(D2y)==-m*9.8-h*diff(Dy),y(0)==0,Dy(0)==v0*sin(alpha),D2y(0)==-9.8);
disp('y(t)=');
pretty(y(t));
disp(y(t));
%Ve do thi
xn=input('Ban muon ve do thi khong(C/K): ','s'); 
disp(' ');
if xn=='c' || xn== 'C'
disp('3. Ve do thi quy dao chuyen dong:'),disp(''); 
fplot(subs(x(t)), subs(y(t)), [0 time]);
while xn=='c' || xn== 'C'
xlabel('x(t)');
ylabel('y(t)'); grid on; shg;
xn=input('Ban muon ve do thi voi gia tri alpha khac khong(C/K): ','s');
if xn=='c' || xn== 'C'
    if (dvgoc==1)
   alpha=input('Nhap goc nem (Rad): ');
elseif (dvgoc==2)
   alpha=input('Nhap goc nem (Deg): '); 
   alpha=alpha*pi/180;
    end
xn2=input('Ban muon giu lai do thi cu khong (C/K): ','s'); 
if xn2=='c' || xn2== 'C'
   hold on;
elseif xn2== 'k' || xn2== 'K'
hold off;
end
fplot(subs(x(t)), subs(y(t)), [0 time]);
end
end
end
How can i add more curve in this code 

[A]

HOW CAN I DO LIKE THIS
clc;
syms m g v0 dvgoc alpha h time t xn xn2; %Khai bao cac bien
disp('XÁC DINH QUY DAO CHUYEN DONG NEM XIEN TRONG TRONG TRUONG CO LUC CAN MOI TRUONG'), disp(' '), disp(' ');
disp('1. Nhap cac gia tri can thiet:'),disp(' ');
m=input('Nhap khoi luong cua vat m (kg): ');
g=input('Nhap gia toc trong truong g (m/s^2): ');
g=-g; %Doi dau gia tring de phu hop voi he truc toa do duoc chon
v0=input('Nhap van toc ban dau cua vat ve (m/s): ');
dvgoc=input('Chon don vi goc (1:rad, 2:deg): '); %Tuy chon don vi goc
if (dvgoc==1)
    alpha=input('Nhap goc nem (Rad): ');
elseif (dvgoc==2)
     alpha=input('Nhap goc nem (Deg): '); 
     alpha=alpha*pi/180; 
elseif (dvgoc==2)
end
h=input('Nhap he so luc can moi truong h: '); 
time=input('Nhap thoi gian bay cua vat t (s): '); 
x(t)=dsolve('m*D2x=-h*Dx', 'Dx (0)=v0*cos(alpha)', 'x(0)=0');
disp('x(t)=');
pretty(x(t));
y(t)=dsolve('m*D2y=m*g-h*Dy', 'Dy (0)=v0*sin(alpha)', 'y(0)=0');
disp('y(t)=');
pretty(y(t));
%Doan chuong trình duoi phuc vu viec ve do thi 
xn=input('Ban muon ve do thi khong(C/K): ','s'); 
disp(' ');
if xn=='c' || xn== 'C'
disp('3. Ve do thi quy dao chuyen dong:'),disp(''); 
fplot(subs(x(t)), subs(y(t)), [0 time]);
while xn=='c' || xn== 'C'
title('Do thi quy dao chuyen dong nem xien trong trong truong co luc can moi truong ');
xlabel('x(t)');
ylabel('y(t)'); grid on; shg;
xn=input('Ban muon ve do thi voi gia tri alpha khac khong(C/K): ','s');
if xn=='c' || xn== 'C'
    if (dvgoc==1)
   alpha=input('Nhap goc nem (Rad): ');
elseif (dvgoc==2)
   alpha=input('Nhap goc nem (Deg): '); 
   alpha=alpha*pi/180;
    end
xn2=input('Ban muon giu lai do thi cu khong (C/K): ','s'); 
if xn2=='c' || xn2== 'C'
   hold on;
elseif xn2== 'k' || xn2== 'K'
hold off;
end
fplot(subs(x(t)), subs(y(t)), [0 time]);
end
end
end