为什么Emac的方案模式中还有一个额外的换行符？

I'm running ypsilon scheme using Emacs 23's scheme-mode. When I enter an expression in the interpreter, it adds an extra newline (see below). I've never seen this happen for any other interpreter. I know ypsilon isn't doing it, because it looks fine in I'm running ypsilon scheme using Emacs 23's sch