???? - use and any synonyms?

[mr tin]

I have said before that it seems that Chinese has many words related to skill and competence and I have often wondered if this is related to the high value placed on such qualities in Chinese society. Here is another one, this time in the form of a ?? ???? I have two questions. How common is this expression in normal speech and in which situations would it typically be used, ie education or job? Are there any other ??-synonyms that mean skill and competence that immediately spring to mind? Thanks in advance.