🎓 TinyProf's Grammar Workshop

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1. What We're Solving

We need to figure out which preposition fits best in the phrase "worked ___ keeping" — and more importantly, understand why one preposition feels more natural than the others. This is about idiomatic English, which means we're looking at how native speakers actually use these phrases.

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2. The Approach

Prepositions in English are notoriously tricky because they often can't be figured out by logic alone — they're governed by idiom (established patterns of use). Our strategy is to:

• Break down what each prepositional phrase implies
• Test each option against the meaning of the sentence
• Check which pattern is conventionally established in English

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3. Step-by-Step Solution

🔹 Step 1: Understand the Sentence's Meaning

Read the sentence carefully:

> "Their policies had worked ___ keeping the U.S. artificial intelligence edge."

Ask yourself: What is "worked" doing here?

It means the policies were effective/successful at producing a result. The result was maintaining the U.S. AI advantage.

So we need a preposition that expresses effectiveness toward an outcome.

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🔹 Step 2: Test "work IN keeping"

The phrase "work in [gerund]" typically describes a domain or field of activity.

For example:

• "She works in teaching." → She's employed in the field of teaching.
• "He works in designing buildings." → His job involves design.

Does that fit our sentence? We're not saying the policies work in the field of keeping something. We're saying the policies succeeded at achieving an outcome.

❌ "work in keeping" — doesn't fit the intended meaning.

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🔹 Step 3: Test "work FOR keeping"

"Work for [gerund/noun]" usually means working on behalf of something or in exchange for something.

For example:

• "She works for a living."
• "He works for the betterment of society."

It's closer, but it implies purpose or motivation, not effectiveness. It would suggest the policies were trying to keep the edge — not that they succeeded.

⚠️ "work for keeping" — possible but suggests intention, not success.

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🔹 Step 4: Test "work AT keeping"

"Work at [gerund]" is an established English idiom meaning to be effective or to apply effort toward achieving something.

Compare these natural English sentences:

• "The medication worked at reducing inflammation."
• "The training worked at improving his stamina."
• "The policy worked at lowering crime rates."

✅ Notice the pattern: work at + gerund = succeeded in doing something through sustained effort

This matches our sentence perfectly — the policies were effective at maintaining the AI edge.

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🔹 Step 5: Consider a Strong Alternative

It's worth noting that many editors might actually prefer:

> "had worked in keeping..." — No ❌ > "had succeeded in keeping..." ✅ > "had worked to keep..." ✅ (very natural!)

"Worked to keep" (using an infinitive) is arguably the most natural phrasing in modern English journalism. But between the three options you listed, "at" wins clearly.

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4. The Answer

| Preposition | Verdict | Why | |------------|---------|-----| | at | ✅ Best choice | Idiomatic; expresses effectiveness toward an outcome | | in | ❌ Doesn't fit | Implies a field/domain, not effectiveness | | for | ⚠️ Weak fit | Suggests purpose/intention, not success |

> 🏆 "worked AT keeping" is the most appropriate preposition because it follows the established English idiom "work at + gerund", meaning to be effective in achieving something through effort.

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5. 💡 Memory Tip

Think of it this way:

> "Work AT" = your effort hits the target 🎯 > "Work IN" = you're inside a field or domain 🏢 > "Work FOR" = you're on someone's side or working toward a cause 🤝

When you want to say something succeeded in producing a result, reach for "worked at"!

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You're asking exactly the right kinds of questions — this level of attention to prepositions is what separates good writers from great ones! 🌟