I want a customized environment to typeset exercises. Write
\newitem text text text
\newitem text text text
\newitem long text typeset on left column
\newitem text text text
\newitem text text text
\newitem text text text
\newitem long text typeset on left column
\newitem text
get
1. text text text 2. text text text
3. long text typeset on left column
4. text text text 5. text text text
6. text text text
7. long text typeset on left column
8. text
---EDIT---
I have tried the shortlst package but it has some shortcoming like
- doesn't support a float picture inside it for figure;
- couldn't embed an enumerate environment as conditions or conclusions list;
- couldn't set the number of columns in advance.
The multienum' package's implement doesn't fit my need.


enumerate/itemizecan take a floating environment. For (2), what do you mean here? Could you provide another "graphic" that illustrates what you're after? For (3), your original request didn't specify that you're after having a variable number of columns. Would you care to elaborate on the end use, and not just an intermediate look-and-feel as seems to be the case here? – Werner Nov 11 '11 at 03:10\includegraphicswould be better. Some use of a table may be more what you're looking for. – qubyte Nov 11 '11 at 06:47