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Help the dramatic theater critic complete her scathing review of last night's disastrous play by choosing the correct phrasing for each gap.
Not until the lead actor tripped over a prop tree _________________________ that the play was supposed to be a tragedy, not a comedy.
So ___________________________________ that several audience members began reading the safety instructions on the back of their seats just to stay entertained.
did I realize
When a sentence begins with a restrictive or negative adverbial phrase like "Not until...", the subject and auxiliary verb in the main clause must be inverted. Because the realization happened at the same time as the tripping (simple past), we use "did I realize" rather than the past perfect "had I realized".
abysmal was the dialogue
When "So" + adjective is fronted for emphasis, it triggers subject-verb inversion (So + adjective + be + subject). "So abysmal was the dialogue" is the only grammatically correct structure here.