RegEx / computer theory - construct a regEx in alphabetical order

In my grammars - Computer theory class I am trying to create a regular expression in alphabetical order(a-z)

l = {a, b, x, y, z, i, o, u, e, c}

This is what i have come up with using the kleene closure

aeiou(x*, y*, z*, i*, o*, u* e*) 

With the kleene close * thats zero or more so that should force abceioxyz?

We have not been learning this type of form

[^abc]

am i on the right track?

As far as I understand, you want to capture strings with the following format:

• The string contains any number of a's, afterwards any number of b's, then any number of c's, and so on...

Let's consider a derived example: We want all strings consisting of 0 and 1 and that has all 0's before 1's: Therefore, we can simply write 0*1*. Now try to adapt the pattern for more complex alphabets.

the word must be in alphabetical order, so if it contains any a's, they surely must be at the front. likewise, if it contains any b's , they must come after the a's, and nothing can come in between the a's and b's

so we have: a*b*...

and so a pattern emerges.