Thanks to Jeff and Pete!
Both method work well.

Usually I try some codes in *scratch* buffer by "C-x C-e". However, I come
to elisp just a few weeks, I know little about this language, and am often
obsessed with the backtrace.

It is very lucky to have a comprehensive references/docs/codes, and an
active mail-group.

2009/6/9 Peter Dyballa <Peter_Dyballa@web.de>

>
> Am 09.06.2009 um 04:04 schrieb Edmond Halley:
>
>  (local-set-key [C-TAB] 'indent-relative)
>>
>
>
> This is close, you just need to write "tab" in lower-case letters.
>
> Have you learned that you can "test" Elisp statements in the *scratch*
> buffer? You can also try them interactively in mini-buffer and upon success
> find this command with C-x Esc Esc (and then cursor up if necessary).
>
> --
> Greetings
>
>  Pete
>
> Specifications are for the weak and timid!
>
>
>
>