A subject - verb - object - adverbial sentence consists of a subject, a verb, an object, and an obligatory adverbial See the glossary definition . The subject is always filled by a noun phrase or a nominal See the glossary definition clause. The adverbial is normally an adverbial of place; it describes where the object is, might be, or where it ends up. The adverb is obligatory because without it the sentence would make no sense or be incomplete.
The subject in the sentence above is a one-word noun phrase. The adverbial is a prepositional phrase. Without this adverbial the sentence would make no sense; it's an obligatory adverbial. Although most of these obligatory adverbials are related to location, they may include metaphorical senses of location and very occasionally may have other meanings.
Here are a few more examples (click and drag to stop, start and find the sentence you wish to examine):
You can view an analysis of some of the noun phrases in the above examples in the animations below (click on Subject to view each noun phrase).
In the above example without the adverbial the sentence would become: "We place them". This is obviously incomplete. As a transitive verb, "place" requires an accompanying adverbial, usually one of location. As in the case here the location doesn't have to be a physical one.
In the above example the verb is lacking because the sentence is an imperative. In this case the adverbial "out of reach of children" is also one of location. But it is non-specific; it means "any place where children cannot reach them".
In the above example the adverbial is an ing-clause See the glossary definition "plummeting below freezing" ("in Texas" is a separate adverbial). The location here is not a physical one; it is movement to another place on a scale ("below freezing").
In the above example the adverbial is "hidden" - a participle modifier ("year-round" is a separate adverbial). This is still related to location. It means "in a place where it cannot be found".
In the above example the adverbial "within two to three days" is difficult to relate to location (apart from the preposition "within").