Answer:
Dear [Sister's Name],
I hope this letter finds you well. Congratulations on passing your exams! I am so proud of you and all the hard work you put in to achieve this success.
Your dedication and perseverance have truly paid off, and I am confident that you will continue to excel in all your future endeavors. Your success is an inspiration to me, and I hope to follow in your footsteps.
Once again, congratulations on this wonderful achievement. I wish you all the best as you move forward and continue to reach new heights.
With love and admiration,
[Your Name]