How can I write subject and predicate phrases so they can be interchanged for a multiple-choice test and still have subject-verb agreement?

Question

I’m trying to write a large set of multiple-choice test questions that can easily be randomized by interchanging their subject phrases and predicate phrases. I’m having some difficulty finding verbs that have the identical singular and plural forms. I’ve noticed the following examples can be useful, but is there any broader class of verbs or strategy I could use to preserve subject-verb agreement when interchanging?

Examples: (Subject / Predicate, such that each Subject would be grammatically correct with each Predicate)

1. In addition to archiving performances, recordings / BECAME an international publicity engine for artists.

2. The notion of an "interface" / CAN refer to any mechanism by which a performer controls an instrument.

3. John Cage / DIDN’T encourage inventors simply to create electronic copies of traditional instruments.

4. Because it used precise and autonomous machines, electronic music / naturally FIT dance music's need for long-lasting steady beats.

5. The earliest sampling synthesizers / INCLUDED the Hardy-Goldthwaithe Organ and Singing Keyboard.

I’ve observed the following:

1. Modal auxiliary verbs seem like skeleton keys to this structure, but most aren’t useful for test questions (e.g., may, should, will).

2. Many past tense verbs are useful (e.g., performed, included, took inspiration, developed), especially ones that are identical to the singular or plural present tense (as above) or use words that could describe agency or categorization (e.g., included), but when I’m not discussing past events, I find myself relying on “can” too much, and it starts to make the whole thing feel uncomfortably subjunctive (i.e., “Hmm….COULD be….”), unsettling the test takers.

I recognize that the interchanged versions of the sentences introduce some other problems, but I’d at least like to sweep those shortcomings into less noticeable areas.

Can you give me any single or systematic tips to make interchangeable singular and plural subject and predicate phrases grammatically correct?

EDIT: Greg commented that “would” would be useful here, and I agree. It also seems less "iffy" than "can," for some reason.

Can anything more can be learned about “would” that could apply to other words? It could function as:

• subjunctive, hypothetical, or epistemic mood(?), e.g., "John Cage would encourage…”
• potential mood(?), e.g., “The term ‘interface’ would refer to…”
• historical present(?), e.g., “Recordings would become a publicity engine…”

I’m really out of my comfort zone regarding moods, but hopefully this is enough to lead a more qualified individual toward elucidating a useful structure at work here.