Câu 1: Mik thấy đề ko liên quan lắm. Ở trc x,y mà ở sau a,b

Câu 2: 

var i:integer;

s:array[1..6] of integer;

begin

for i:=1 to 6 do begin

write('Nhap so thu ',i,': ');readln(s[i]);

end;

write('Cac so chan la: ');

for i:=1 to 6 do if s[i] mod 2=0 then write(s[i],', ');

readln

end.

Câu 3

var a,i,tong:integer;

s:array[1..100] of integer;

begin

write('Nhap a: ');readln(a);

for i:=1 to a do begin

write('Nhap so thu ',i,': ');readln(s[i]):

tong:=tong+s[i];

end;

writeln('Tong cua day so la: ',tong);

readln

end.

Câu 4

var a:string;

i:integer;

begin

write('Nhap xau: ');readln(a);

for i:=1 to length(a) do a[i]:=upcase(a[i]);

writeln('Sau sau khi in hoa: ',a);

readln

end.

Câu 7

var i,n,s:integer;

a:array[1..100] of integer;

begin

write('Nhap n: ');readln(n);

for i:=1 to n do begin

write('Nhap so thu ',i,': ');readln(a[i]);

if a[i] mod 3=0 then s:=s+a[i];

end;

writeln('Tong la: ',s);

readln

end.