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if/then/else — note: NO semicolon before else:

if age >= 18 then
    WriteLn('adult')
else
    WriteLn('minor');

Multiple statements need a begin/end block:

if x > 0 then
begin
    WriteLn('positive');
    WriteLn('and non-zero');
end
else
    WriteLn('zero or negative');

case statement — like switch, more flexible:

case day of
    1, 2, 3, 4, 5: WriteLn('weekday');
    6, 7: WriteLn('weekend');
else
    WriteLn('invalid');
end;

Case labels can be ranges: 1..9: ...

Logical operators: and, or, not (NOT &&, ||, !). Comparison: =, <> (not equal), <, >, <=, >=.