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单选题小学英语

2023-06-08

Please select the correct option（）。

A．teachers

B．scientists

C．doctors

D．works

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参考答案

B

答案解析

考查上下文语义。根据后面句子意思“他们研究植物、动物和冰块怎样移动”，此空应填scientists，故选B。

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1 Please select the correct option（）。

A．during the autumn season

B．in the spring time

C．in all weathers

D．in the winter

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2 阅读短文，回答问题：

It's one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a cat before, it is still able to detect chemical signals released from it and run away in fear. This has always been thought to be something that is hard-wired into a mouse ' s brain.
But now Wendy Ingram, a graduate student at the University of California, Berkeley, has challenged this common sense. She has found a way to "cure" mice of their inborn fear of cats by infecting them with a parasite, reported the science journal Nature.
The parasite, called Toxoplasma gondii, might sound unfamiliar to you, but the shocking fact is that up to one-third of people around the world are infected by it. This parasite can cause differ-ent diseases among humans, especially pregnant women--it is linked to blindness and the death of unborn babies.
However, the parasite's effects on mice are unique. Ingram and her team measured how mice reacted to a cat's urine(尿)before and after it was infected by the parasite. They noted that normal mice stayed far away from the urine while mice that were infected with the parasite walked freely around the test area．
But that's not all. The parasite was found to be more powerful than originally thought—even after researchers cured the mice of the infection. They no longer reacted with fear to a cat' s smell, which could indicate that the infection has caused a permanent change in mice's brains.
Why does a parasite change a mouse's brain instead of making it sick like it does to humans? The answer lies in evolution.
"It's exciting scary to know how a parasite can manipulate a mouse's brain this way," In-gram saiD． But she also finds it inspiring. "Typically ff you have a bacterial infection, you go to a doctor and take antibiotics and the infection is cleared and you expect all the symptoms to also go away." She said, but this study has proven that wrong. "This may have huge implications for infec- tious disease medicine."
The passage is mainly about__

A．mice's inborn terror of cats

B．the evolution of Toxoplasma

C．a new study about the effects of a parasite on mice

D．a harmful parasite called Toxoplasma gondii

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3 The underlined part "hard-wired" in Paragraph 1 probably means__

A．deeply rooted

B．quickly changed

C．closely linked

D．deeply hurried

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