A nasal ending hidden by character recognition

A learner recognizes the characters 身 and 生 and knows their meanings, but reads both Pinyin forms as shēn. The exercise supplies the forms shēn and shēng and asks which component differs. Another learner proposes changing the first tone or replacing sh with s, although neither change matches the supplied contrast. A useful practice sequence keeps those shared components stable, compares the nasal endings and then returns the words to meaningful phrases. No phonetic audio or examiner rating is supplied, so the response should not pretend to diagnose the actual recording. It should distinguish the written contrast from the further work needed to produce and hear it reliably. The aim is precise feedback about one feature, not a general claim that speakers of a particular language all make the same error.