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,练习记笔记技巧和复述。废话少说,下面开始:



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。

Tis the season for infections. And if you wind up with a prescription for penicillin or its relatives, you’re getting a gift that’ll give those unwelcome bacteria a double whammy. Because a new study shows that the penicillins wipe out infections by delivering a lethal one¨Ctwo punch. The findings are revealed in the journal Cell.

Scientists have long known that penicillin and its relatives disrupt the assembly of the bacterial cell wall, a tightly woven mesh made of peptide-studded sugars called peptidoglycans. The drugs bind to enzymes that produce peptidoglycans and then link them together. That interaction shuts down the enzymes’ cross-linking capabilities. Without the cross-links, the cell wall collapses. And the bursting bacteria die.

But the full effect of the antibiotic, in widespread use since World War II, was not appreciated til now.

In the new study researchers treated bacteria with a form of penicillin and then watched what happened to the cell wall components. As expected, the drug blocked cross-link formation. But the surprise was that the enzyme that can no longer forge links doesn’t just sit there. It continues to churn out unlinked peptidoglycans which the bacteria don’t want piling up, so they rapidly degrade.

This futile cycle of synthesis and destruction depletes bacterial resources, speeding the path to [sound effect of annihilation]. The finding could point the way toward the development of new antibiotics ones that are similarly multitalented when it comes to wiping out what ails you.

–Karen Hopkin


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