Good learners willkeep practicing what they have learned，and they are not afraid of making mistakes.

這里，what是practicing后的賓語從句嗎？will keep practicing是謂語部分嗎？

what?they have learned?是practicing的賓語從句，what?在從句中作?have learned的賓語。will keep是謂語動詞，practicing what they have learned 是動名詞短語作will keep的賓語。