英文文法詞性問題has tripled compared with?

1，這類以現在或过去分詞當介詞使用，我們稱之為邊緣介繫詞(marginal preposition)，例如I ask several questions concerning his suggestions.(現在分詞concerning )另Given his inexperience,he has done a good job.(過去分詞given)
2，本句可寫成compared with the same time last year,the number of measles cases reported worldwide in the first three months of 2019 has tripled.更易懂，所以在原句compared with the same time last year是介詞片語當副詞修飾tripled

not adv, not prep; but 
since; considering that:-
eg:-How can I eat measles(when considering that) they had increases 3 times?
eg:-The Mayor will visit the town in May, (when considering, during which time) hw will open the new stock-market house.

compared的詞性要看你理解句子，只是由於tripled和compared之間省去了一些英語人不會寫的字：

... has tripled when they (=number of measles cases reported worldwide) were compared with the same time last year.

由此看compared可是PVV，寫作的文法為報告式。