汉译英,<<哈利.波特3>>里的一句话

I solemnly swear that I am up to no good.

本句的前后文如下：
He took out his wand, touched the parchment lightly, and said, "I solemnly swear that I am up to no good."

And at once, thin ink lines began to spread like a spider's web from the point that George's wand had touched. They joined each other, they crisscrossed, they fanned into every corner of the parchment; then words began to blossom across the top, great, curly green words, that proclaimed:

Messrs. Moony, Wormtail, Padfoot, and Prongs

Purveyors of Aids to Magical Mischief-Makers are proud to present THE MARAUDER'S MAP

I am solemn to swear me and will never executive officer

I swear I won't do anything good!

I pledged dignified I do the good deed in no way

I swear I won't do anything good