3rd person plural feminine perfect passive. OK – What’s a feminine plural ending on the participles? There are two – portatae sunt and remotae erant. Must be one of them. Now, you want the PRESENT perfect. Of those two, which has a form of ‘to be’ in the PRESENT tense? Yep, it’s portatae sunt.

Look at another one:

1st person plural masculine future perfect passive. Masculine plural endings? Three this time: territi eratis, rogati erimus, moti erunt. Which one has a first person plural form of ‘to be’? Can’t be ‘eratis’ – that’s second person. Can’t be ‘erunt’ – that’s third person. What’s left? Rogati erimus

Use those same techniques on the others – once you have a system, it’s really pretty simple.
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