couple;  pair
Courting couples
They go everywhere as a couple
A pair of shoes/gloves/socks/ear-rings
twin;  double
Twin towers in New York
A double room;  a double garage
A double wedding
To sleep double
(     làm đôi ) in half/two;  into halves To cut a loaf in half/two;  to cut a loaf into halves
To tear a newspaper in half/two;  to tear a newspaper into halves
this is an expensive meal - let's go half and half/let's go halves
Fold the letter in two before putting it in the envelope;  fold the letter double before putting it in the envelope;  double the letter   before putting it in the envelope