PTE考生目前最大的问题之一就是练习题缺乏。除了有限的基本官方书（PLUS，Testbuilder, OG）之外,就没有题了。很多英语基础不是很扎实的同学很难找到练习材料。墨尔本文波雅思PTE培训学校专门为墨尔本，悉尼PTE考生准备了适合PTE听力阅读练习的科学60秒。各位PTE同学可以练习PTE听力中的summarise spoken text和PTE口语中的retell lecture，PTE听力口语-科学60秒-Frosty Moss练习记笔记技巧和复述。废话少说，下面开始：
Laser Light Coaxes Damaged Rodent Tooth Repair
60秒科学节目（SSS）是科学美国人网站的一套广播栏目，英文名称：Scientific American – 60 Second Science,节目内容以科学报道为主，节目仅一分钟的时间，主要对当今的科学技术新发展作以简明、通俗的介绍，对于科学的发展如何影响人们的生活环境、健康状况及科学技术，提供了大量简明易懂的阐释。
Ouch! About a quarter of all school-age kids will break or otherwise damage a tooth. Adults have their share of cracked chompers, too.
But what if fixing a busted bicuspid was as easy as zapping it with a laser? Preliminary work with young rats has moved dentistry a small step in that direction. A new study finds that shining a low-power laser on damaged rat teeth activates molecular growth factors already present in the tissue. These growth factors cue stem cells to generate dentin, the bonelike substance that teeth are mostly made of.
Researchers also found that when mice were missing those growth factors or when the factors were blocked from working, the stem cells would not regenerate dentin when exposed to laser light. That finding confirms the important role these signaling pathways play in dental development. The study, led by David Mooney at Harvard’s Wyss Institute, is in the journal Science Translational Medicine. [Praveen R. Arany et al, Photoactivation of Endogenous Latent Transforming Growth Factor®Cβ1 Directs Dental Stem Cell Differentiation for Regeneration]
Could a light-based treatment for cavities and chipped teeth eventually be in the offing for people? The researchers plan to investigate that possibility for human teeth, both baby and adult. But until then, chew carefully. And don’t lead with your chin.
–Dina Fine Maron