have something down pat
US /hæv ˈsʌmθɪŋ daʊn pæt/
UK /hæv ˈsʌmθɪŋ daʊn pæt/

1.
烂熟于心, 完全掌握
to know or understand something perfectly
:
•
After weeks of practice, she finally has her lines down pat for the play.
经过几周的练习,她终于把台词背得滚瓜烂熟了。
•
He's been working on that presentation for so long, he must have it down pat by now.
他为那个演示文稿准备了这么久,现在肯定已经烂熟于心了。