I am pretty sure that the items that I ordered should have arrived this morning.(meaning I expect that the items arrived this morning) is the sentence with 'should have' correct and also it's common to say in USA.
Top answer
Being ‘pretty sure’ has the same meaning as ‘should’, so it would be repetitive to use both. )
— Wilpeter
Being ‘pretty sure’ has the same meaning as ‘should’, so it would be repetitive to use both.
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Being ‘pretty sure’ has the same meaning as ‘should’, so it would be repetitive to use both. “I am pretty sure that the items (that) I ordered will have arrived this morning.” or “The items that I ordered should have arrived this morning.” (it is common to avoid repeating ‘that’ in a sentence when unnecessary to the understanding.)
I tend to disagree with Clive on this one: If items ordered were scheduled to arrive this morning, one cannot be ‘pretty sure they arrived’ unless this is an extremely competent shop. 'Should have arrived' in this case is simply 'they were scheduled to arrive'.
I am pretty sure the items I ordered (last week) should have arrived this morning (but they didn't, or you're at the delivery address to check and you're not entirely sure of the delivery date).
The first part is about the whole sentence, the second is about receipt - it works for me! (I'd take out both instance of the word that).