Use "go slack" in a sentence

1. It was just that she didn't sleep, and so her brain was relaxed and let the reins of her thinking go slack

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2. He concentrated closely upon the steel track because he would need to pull when the track moved ever so slightly towards him and then go slack on the thread as it swung away

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3. Fury wreathed across his features he started to raise his gun, only to have his features go slack with surprise and have his eyes track down to the blade stuck fast within his chest where a heart should’ve been

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4. I let the reins go slack and Relentless surged forward into the night

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5. I watched her face go slack with shock and before she could burst out with the usual questions I said, “You’re worth the wait anyway

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6. Every nerve in my body seemed to go slack

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