Sometimes VT can last for 30 seconds or less (unsustained), and it might not cause any symptoms, although it causes inefficient heartbeats.

有时室速的持续时间不会超过半分钟（非持续性室速），也不会有任何症状，虽说这期间心脏会有一些无效的跳动。

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All evidence to date suggests that isolated instances of limited, unsustained human-to-human transmission can be expected from avian influenza viruses in humans.

迄今为止，所有证据表明，可预期人间禽流感病毒有限、非持续人际传播的孤立事例。

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Unsustained by anything resembling directorial control, Luke Wilson holds the screen for almost two hours in a front-and-center turn as Jack Harris, a Houston-based business fixer who, in the mid-nineties, had an Internet version of greatness thrust upon him.

NEWYORKER: Middle Men