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。悉尼文波雅思PTE培训学校专门为澳洲，尤其是悉尼、墨尔本的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。
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。
This is Scientific American — 60-Second Science. I’m Christopher Intagliata.
Fossilized skulls and skeletons found in European caves gave us our first glimpse of our ancient cousins, the Neandertals. And a finger bone, found in a Siberian cave, first indicated the existence of another relative—the Denisovans. But fossils are hard to come by. So here’s another option: analyze cave floors to see if they contain
“We find ancient hominins, we find Neandertal mitochondrial DNA, and
Denisovan mitochondrial DNA.”
Viviane Slon, a geneticist at the Max Planck Institute in Germany.
She and her team found that molecular evidence by testing teaspoonfuls of
sediment from seven different caves. And they screened specifically for mitochondrial DNA—because there’s a lot more copies of it in cells compared to nucleus DNA, which has just one
set per cell.
The researchers uncovered genetic evidence of Denisovans where you
might expect—at Denisova Cave in Siberia. Which showed that their strategy was sound.
They found Neandertal DNA there too, and at three of the other seven caves—including a cave where no Neandertal fossils have ever been found, only artifacts and animal bones. And
they found the DNA of some surprise guests, too: “For example, the woolly mammoth, or the woolly rhino. We have cave hyenas and cave bears.” The study is in the journal Science.
This preliminary success, Slon says, means the method could be
a good complement to traditional surveys. “We’re not trying to replace working on ancient DNA from fossils, but rather open all the archaeological sites where there are no
hominid fossils for genetic analyses.” Leading, hopefully, to a broader census of our ancient relatives.
No bones about it.
Thanks for listening for Scientific American — 60-Second Science Science. I’m Christopher Intagliata.