I am playing this piece and have difficulty in bar 9, 11, 13 (left hand).Music score:https://musescore.com/user/37774/scores/55817#For example, in bar 9, my finger is 2-4 for first chord and 2-4 for second chord.I have trouble making an octave jump.For these bar, my piano teacher told me to practice by not looking at piano keys.Could you please advice me how to practice these bars?Thanks.