在这重要的一亿年的周期内缺乏化石(记录),关于这一点,有一种解释是早期的动物是软体动物,所以它们无法形成化石。
One interpretation regarding the absence of fossils during this important 100-million-year period is that early animals were soft bodied and simply did not fossilize.
新南威尔士大学的一项新研究发现,在工作周期间,澳大利亚的父亲们每天单独陪伴孩子的时间平均只有一分钟多一点。
A new study from the University of New South Wales has discovered that during the working week, Australian fathers only spend an average of just over a minute each day alone with their children.
上午九点半的时候,完整的红黄绿信号灯变换周期大概为140秒。
At 9:30 am, the full red/yellow/green signal cycle might be 140 seconds.
Cells can stop in their lifetime at some point in the cell cycle and persist for long periods of time.
细胞生命期可以停止在细胞周期的某个点,并保持很长时间
Second thing, we started talking about the periodic table and I believe that it's a hallmark of any educated person in the 21st century who is technically literate to know the periodic table by heart.
第二点,我们之前讨论过元素周期表,我相信这是个标志性的特征,对于那些在21世纪里,用心去学习,元素周期表的人来说。
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