Recently I’ve had several occasions where I wanted to kill to the beginning of the current sentence. No problem, I thought, I’ll just write a quick bit of Elisp like
(push-mark nil nil t) (backward-sentence) (kill-region)
and bind it to some convenient key. After a little investigation I discovered that Emacs already provided backward-kill-sentence and that it was bound to【Ctrl+x Delete】 so there was nothing to do—the functionality was already there.
That got me thinking about killing to the end of the current sentence. To do that I’ve just always used 【Meta+z .】 but it turns out that Emacs also has a kill-sentence to do the job. It’s bound to 【Meta+k】, which makes sense since you use 【Meta+a】 and 【Meta+e】 to move to the beginning and end of a sentence.
Emacs really is the journey that never ends. There’s always something else to learn.