Writing Question!

<p>This was from the May QAS sat...</p>

<p>"In the Bay of Fundy the rising tide produces a so powerful inward surge that it actually reverses the normal flows of several rivers."</p>

<p>The correction is to switch it to "an inward surge so powerful" but I don't understand why it cannot be "so powerful of an inward surge." Aren't they both grammatical?</p>

<p>The problem is with “of.” The correct structure is so powerful an X, where X is a noun. When you add the “of,” it becomes a direct object.</p>

<p>Okay thanks! That actually makes sense</p>