[xupybd]

The only counterexample I can think of is the present tense.

For example: You have kids, you should have life insurance.

[nlh]

Yes - you're absolutely right. I should have (ha!) specified I meant in the context of a past participle ("you should have <verbed>"), not the present suggestive (is that the right term?) -- eg "you should have <object>" or even "you should <verb>"

Man, grammar is weird. ;)