1. Must've slipped my mind.
slip my mind：突然忘记
例句：
Oh, it's nearly slip my mind! Dannie ask me to give you this.
哦，差点忘了！丹尼要我把这个给你。
2. Yes, well, as slippery as your mind is...
slippery：狡猾的，不可信的
例句：
That guy is a slippery character.
那人是一个狡猾的家伙。
Don't lend any money to that slippery person.
不要借钱给那个不可靠的家伙。
3. I shall practice my curtsy.
practice curtsy：训练礼仪
4. Don't turn your back on me, Scar.
turn one's back on：不理不睬，拒绝
例句：
I can't turn my back on him when he needs help.
在他需要帮助的时候，我们不能不管。
Did you really turn your back on his invitation?
你真的拒绝了他的邀请吗？
No nation can afford to turn its back on global opportunities.
没有一个民族能拒绝全球的机遇。