1. Mary learns better than I.
=>I don't ..learn as well as Mary..
2.Barbara runs faster than John.
=>John doesn't ..run as fast as Barbara..
3.He enjoys playing badminton more than I do.
=>I don't enjoy ..badminton as much as him..
4.Mrs Ha uses 6000 liters of water a month.Mrs My uses 12000 liters of water a month.
=> Mrs My uses twice ..liters of water a month than Mrs.Ha ..