A
It's not every day that United States history mixes with microbes (微生物)in the soil.But when the grassland on the National Mall in Washington, D．C.was replaced, it offered scientists the opportunity to study changes in the soil beneath.
The work focused on the bacteria present in the soil.To the researchers' surprise, the communities of microbes did not change a lot before and after the replacement.These communities in the soil are known as the soil microbiome(微生物群).
“My lab is interested in how microbes can move around in the environment, and how they change and adapt as a result of this movement，” explains Jo Anne Crouch，the lead author of the study.“We thought that the new ‘imported’ turf(草皮)from New Jersey would introduce different communities of bacteria to the National Mall.However, we found that they weren't significantly different.”
Crouch's work focused on turf grass, defined as a large area of green grass.It is made up of the grass，its roots, and the soil and microbes found with them.
Think of the soil microbiome as similar to the collection of microbes found in the human body.When the microbes are out of balance, it can make someone sick.Crouch says it's the same for the soil microbiome.Many of the worst diseases in crops or other environments are linked with changes in the soil microbiome.
Additionally, Crouch says that even though the changes between the soils were small, scientists are also starting to appreciate that sometimes a really important microbe is a rare one.This means it would be hard to observe but could greatly affect how the groups function as a whole.“Agricultural areas and other natural spaces are highly and easily hurt by negative changes，” she says.“Microbiomes offer an almost entirely new opportunity to influence interactions among plants and microbes to improve plant productivity and health.”
[语篇解读] 本文主要介绍对微生物群落的研究，该研究对农业是有益的。
1．Why did the researchers feel surprised when they focused on the bacteria in the soil?
A．More bacteria appeared in the soil.
B．Microbes were replaced obviously.
C．Soil microbiome almost remained stable.
D．The soil microbiomes damaged the environment.
C [细节理解题。根据第二段中的“To the researchers' surprise，the communities of microbes did not change a lot before and after the replacement.”可知，让研究者惊讶的是土壤微生物群落变化不大，C项与该意思相符。]
2．By studying the turf grass, what did Crouch and her team find?
A．Microbes grew faster in their own community.
B．Soil microbiomes were different in different places.
C．Turf grass adapted to the environment nearby very soon.
D．Similar communities of bacteria were brought by turf grass.
D [细节理解题。根据第三段第二、三两句可知，通过研究草坪草，克劳奇和她的团队发现草坪草带来了类似的细菌群落。]
3．Why did the author mention the microbes in the human body?
A．To indicate the two play a similar role.
B．To prove they are both the causes of diseases.
C．To examine the environments people live in.
D．To analyze the changes of human microbes.
A [推理判断题。根据第五段第一句“Think of the soil microbiome as similar to the collection of microbes found in the human body.”可知，作者提到人体内的微生物是为了表示，它们两者起了相似的作用。]
4．What does Crouch mean in the last paragraph?
A．Microbes are still as hard to observe as before.
B．Studies on microbiomes can be beneficial to agriculture.
C．Scientists are still puzzled about the effect of microbiomes.
D．Too many microbiomes in the soil mean no harm to plants.
B [推理判断题。根据文章的最后一句提到“微生物群落提供了一个几乎全新的机会来影响植物和微生物之间的相互作用，以提高植物的产量和健康。”由此可知，微生物群落的研究对农业是有益的。]
