A: I haven't seen you for a long time. What are you doing?
B: I've been keeping on studying the piano.
A: How's it going?
B: Too bad. I failed the test for degree. So I have to set my jaw to do more practice.
set one’s jaw
exp. To be or become resolute and determined (to do something). （下决心对付困难，咬紧牙关）
e.g. The violence of her emotion made her set her jaw, as if were, against giving way.
e.g. The snow was blowing in his face but the set her jaw and went on.
1. keep on something/doing something：继续做某事
e.g. How am I to work if you keep on chattering?
e.g. You and I keep on attending to trifles instead of what's important.
e.g. I'm glad you began at once, and hope you will keep on.
2. do some practice：练习
e.g. She went on to do some oral practice after the dictation.
e.g. I need to do some Italian practise before my business trip.