Beethoven rondo op. 129 in the page before the last after the calando where we play " a tempo" with g major chords. any practicing , fingering tips,

Practice measure by measure. Start slow and you can gradually increase the tempo. Repeat until you understand and memorize, make lots of notes on your misic sheet. And if it's G Major, just may mind to the finger patterns. Try lying down of the ground and playing the quick parts, it's hard, but the gravity will pull your bow down, it'll train you to keep your bow and arms in the appropriate positions.