According to Carol Sansone, Ph. D., a psychology professor at the University of Utah, one type of reinforcement must be present for self-change, two would be better than one, and three would be best.

犹他大学的心理学教授，卡罗尔·桑松尼博士说：对个人的改变来说，一种强化是必须的、两种类型的强化就更好了，如果有三种那就再好不过了。

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According to Dr. Steven D. Rauch, a professor of otolaryngology at Harvard, there are four major areas for concern: ear hygiene, noise injuries, age-related hearing loss and ear health emergencies.

哈佛大学耳鼻喉科教授斯蒂文·D·劳赫指出，有四点需要予以关注：耳部卫生、噪音伤害、与年龄有关的听力损失，以及突发性的耳部健康事件。

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Research by Daniel Willingham, Ph. D. , a psychology professor at the University of Virginia, showed that repetition increases the probability of success.

弗吉尼亚大学的心理学教授丹尼尔·威灵汉博士的研究显示重复增加了成功的可能性。

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Edna Medford is a professor of history at Howard University in Washington,D.C.

VOA: special.2009.02.27

W.Joseph Campbell is a communications professor at American University in Washington,D.C.

VOA: special.2009.08.28

Professor James Gray at American University in Washington,D.C.

VOA: special.2010.04.13

Guidelines suggest that all pregnant and lactating women should take Vitamin D and Professor Nussey said many working in the field believe there has been a resurgence of the disease is related to the fact that recommendation is not followed.

BBC: What is rickets?

"This is a moment of transition, a period of re-alignment in Italian politics, " said Professor D'Alimonte.

BBC: Napolitano aims to break Italy's political deadlock

It's all part of the direct approach embraced by Gary W. Loveman, Harrah's chief executive, since he took his celebrated leave in 1998 from the Harvard Business School, where he'd been a professor.

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