Question

select the two prepositional phrases.
a british biotechnology firm is experimenting with genetically modified mosquitoes to combat dengue fever, a mosquito - borne illness that threatens the lives of millions.

Explanation:

A prepositional phrase is a group of words that begins with a preposition and ends with a noun or pronoun (the object of the preposition). In the given sentence, "with genetically modified mosquitoes" starts with the preposition "with" and "of millions" starts with the preposition "of".

Answer:

with genetically modified mosquitoes, of millions