Sentence Correction (SC) | The federal rules aimed at protecting human subjects of medical experi

This sentence works either with or without the second "that" (although it's much easier to understand if there are two instances of "that" than if there's just one).

One thing that should be very clear, very quickly, is that the verbs in the two parallel parts should appear in identical tenses. The parts describe two things that are both ensured by the same set of rules—definitely simultaneous observations.

The
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