prepositional-phrases in passive sentence

Question

I have read we can use Prepositioal Phrases as both adjective phrase and adverb phrase. But how can we differ them from adjective or adverb when changing them into passive? For example,

Evaporation of sweat takes heat from the body.

In this sentence I can't decide whether from the body is "adjective phrase or adverb phrase". So trying to change it into passive structure, there may be two possible answers.

1. Heat is taken from the body by the evaporation of sweat.

2. Heat from the body is taken by the evaporation of sweat.

Which sentence is suitable for the meaning of the active sentence given?

Answer 1

There is no way to know. 

You are quite correct.  The prepositional phrase "from the body" in your active voice example could sensibly modify either "heat" or "takes" from that position.  The distinction, which is very clear in your passive voice examples, simply is not marked in the active voice. 

Your two possible answers are, in fact, both possible.  Without further context, I see no clear reason to prefer one over the other. 

Answer 2

Heat is taken from the body by the evaporation of sweat.

This means the evaporation of sweat causes heat to come out of the body.

Heat from the body is taken by the evaporation of sweat.

This means heat that was already outside of the body is taken by the evaporation of sweat. Sweat is not drawing heat outside of the body but skimming off what is there.

The non-passive example has "heat from the body" as what comes after takes, so if you say "Heat from the body is taken..." you are most directly converting that sentence to passive form.