3. While he was working in the factory, he was anadvanced worker. → ____ in the factory, he was anadvanced worker. → ____ _____ in the factory, he was anadvanced worker.
3. While he was working in the factory, he was anadvanced worker. → ____ in the factory, he was anadvanced worker. → ____ _____ in the factory, he was anadvanced worker.
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