1) Betty's only got half the money she needs to buy a new smartphone.
TWICE
2) As he gets more experience he seems to work more efficiently.
THE
3) It's the most difficult exam I've ever taken.
MORE
4) Driving a car is easier than driving a lorry.
SO
5) Mark is eighteen years old and my brother is eighteen years old too.
SAME
6) Rick was too impatient to wait for us to make the next move.
ENOUGH