a) this is [more or less] all I planned to tell about {XYZ, the subject}. Thank you for following my exposition. There is some time left, if you have questions related to the subject, I will be glad to answer. b) I did my best, now please go away, I am tired of seeing your dumb faces having difficulties following my great ideas. :)

你可以说That's it或者I'm done，再地道点的就说一个Period就行了，同时这还有“没啥可说”的另一种意思