brush up (on)	practise and improve your skills or knowledge of something
come (a)round (to)	change your opinion or decision because someone has persuaded you to agree with them
come up with	think of somethink such as an idea or a plan
face up to	accept sth and try to deal with it
figure out	1/2) be able to understand sth or solve a problem
figure out	2/2) understand what someone is like and why they behave in the way they do
hit upon	1/2) suddenly have an idea 2/2) discover sth by chance
make out	1/2) see, hear or understand someone or something with difficulty 2/2) suggest, imply
mull over	think carefully about something over a period of time