He ran _____ that the defenders couldn't catch up with him.

Step 1: Analyze the question The sentence is "He ran _ that the defenders couldn't catch up with him." The word "that" introduces a result clause, which tells us we need a so... that structure (result/consequence).

Step 2: The concept The pattern is:

so + adjective/adverb + that + result

• She was so tired that she slept immediately. (adjective)
• He ran so fast that nobody could catch him. (adverb)

Here, "ran" is a verb, so it needs an adverb: "fast" (which is both an adjective and an adverb, with the same form).

Step 3: Test each option

• A. very fast: "Very" doesn't work with "that" to show a result. "He ran very fast that..." is ungrammatical. It would need to be "very fast, so that..." or just "very fast and..."
• B. much faster: The comparative "faster" needs "than", not "that". It would not give a result clause.
• C. so faster: "So" cannot be combined with a comparative form. This is wrong.
• D. so fast: This fits the "so + adverb + that" pattern correctly. ✅

Step 4: Answer "He ran so fast that the defenders couldn't catch up with him.

Step 5: Exam tip When you see a blank followed by "that", check for so... that (result) or such... that.

• so + adjective/adverb (so fast, so tall)
• such + (a/an) + noun (such a fast runner)

Also remember: so never goes with a comparative (so faster ❌).