17. I recognized his face but I forgot his name so I just smiled and said, "Hi".
18. Anna stopped taking the piano lessons because she was convinced that she could never learn to play the piano.
Hoặc: Anna was convinced that she could never learn to play the piano so she stopped taking lessons.
20. These animals scattered into the trees because they were hunted by lions.
Hoặc These animals were hunted by lions so they scattered into the trees.