In addition to being an exercise on tense, number, and prepositional phrases, this is a challenging exercise in what writing teachers call "invention." Students will need to "invent" the details of identity and extension in time and space. Weak writers often omit these details, and this omission accounts for much of the weakness in their writing, both in terms of details and in terms of main-clause length, a major yardstick of syntactic maturity.
     Note that "identity" and "extension in time or space" are the first two of Hume's three basic logical categories, so this is also an exercise in basic logic.

1. The shiny swords {of the soldiers} [Adj. (identity) to "swords"] clashed {for hours}

[Adv. (how long) to "clashed"] {in the bloody field} [Adv. (where) to "clashed"]. [Past,

plural]
 

2. The yellow and gold leaves will fall {into the fields} [Adv. (where) to "will fall"] 

{in the windy days} [Adv. (when) to "will fall"] {of autumn} [Adj. (identity) to "days"].

 [Future, plural]
 

3. {During the holidays} [Adv. (when) to "does buy"], does the typical man buy many

(DO) {of his presents} [Adj. (identity) to "many"] {at the mall} [Adv. (where) to "does

buy"] the night ^[NuA] {before Christmas} [Adj. (identity) to "night"]?  [Present, singular]
 

4. {In the spring} [Adv. (when) to "planted"] the farmer planted acres (DO) {of

corn} [Adj. (identity) to "acres"] {in different parts} [Adv. (where) to "planted"] {of his

fields} [Adj. (identity) to "parts"]. [Past, singular]
 

5. {In early spring} [Adv. (when) to "babbles"] the boisterous, bubbling brook babbles

{around the melting ice} [Adv. (where) to "babbles"] {of winter} [Adj. (identity) to "ice"].
 

6. Charitable doctors {without borders} [Adj. (identity) to "doctors"], {in the future}

[Adv. (when) to "will save"], will save many more people (DO) {around the world}

[Adv. (where) to "will save"].  [Future, plural]