◎◎◎ coronavirus ⪢⪢
Coronaviruses are a large group of viruses. They consist of a core of genetic
material surrounded by an envelope with protein spikes. This gives it the appearance of a crown. 'Crown' in Latin is called 'corona' and that's how these viruses get their name.
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○○○ topology ⪢⪢
Topology is a branch of
math, which is kind of like geometry. It studies shapes and spaces, but ones that are arbitrarily stretchy and bendy. It's sometimes called rubber sheet geometry.
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○○○ Anna Matteo ⪢⪢
Metcalf says the decision for the word of the year is not based on science. Instead, he says the A.D.S. chooses from words that express the concerns and stories of the past year. For VOA Learning English, I'm Anna
Matteo.
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○○○ Φ ≈ 1.618 ⪢⪢
Keplar observed that the relationship between a number in the Fibonacci sequence and the previous number more and more closely approaches the irrational number Φ, the longer the sequence is continued. #
math
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○○○ expect ⪢⪢
Now if a is greater than 0 and b was greater than 1, then we can expect the graph to look something like this. If a is greater than 0 and b is greater than 0 but less than 1, then the graph will look something like this.
#
math
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○○○ nebula ⪢⪢
The solar system came into being about 4.5 billion years ago when a cloud of interstellar gas and dust collapsed resulting in a solar nebula, a swirling disk of
material that collided to form the solar system.
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○○○ strain ⪢⪢
People feared starvation and disease and the relations between villagers were _____ed. To make
matters worse, 1692 brought one of the coldest winters on record.
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