Sometimes the adverb is obligatory and unmovable

Consider this sentence:

(1) He put the bag down.

The parts of the sentence are He (S) / put (V) / the bag (O) / down (A). The removal of A (adverbial) would render the sentence incomplete. In other words, the A is obligatory.

Some teachers call this sentence SVO but that would make “the bag down” the object of the sentence, which of course is not true. It is true the V and A make a set. We can see this by rearranging the syntax elements to

(2) He put down the bag.

By doing so we can explain it as SVO where put down is the single unit of V. A problem arises when the A is a longer element, and cannot be moved easily like (2). For example,

(3) He put the bag on the overhead baggage shelf.

is a perfectly good sentence and again it is SVOA. But if we try to rearrange it as in (3a)

(3a) He put on the overhead baggage shelf the bag.

we find the sentence to be clumsy and unnatural.

For this reason it is better to teach SVOA rather than try to slim the sentence patterns to less for the sake of brevity. Sometimes this can be too much to be useful.