1.Hung’s brother  drivers carryfully than he does drives as carefully as he does / drivers carryfully than he doesn’t drives as carefully as he does.
2.Some years ago the laboratory  in my school was worse equipped than now.
3.Quang works harder so he often gets better marks than Nam.
4.Minh drives more carelessly than Trung so he often has had an accident.
5.Going by a bus is slower than going by a taxi but it costs less than a taxi