演员们必须快速记住他们的台词以备表演。

Actors must ___learn their lines quickly for performances.

作为作业，我们必须熟记一篇著名演讲。

For homework, we had to ___learn a famous speech by heart.

他教我们一些有效记住角色的技巧。

He showed us tricks to ___learn our roles effectively.