『新东方在线托福阅读』为托福考生准备了ETS托福TPO/【学术文章】#8阅读练习：The word “essential” in the passage is closest in meaning to真题题目及答案解析，TPO/【学术文章】#8阅读原文范文音频翻译

托福TPO/【学术文章】#8阅读原文The word “essential” in the passage is closest in meaning to题目答案及解析-新东方托福官方网校手机版

树木年轮学是通过统计树木年轮数量确定树龄，并测量轮宽以推断历史气候特征的技术。

Dendrochronology is the technique of counting tree rings to determine a tree’s age and measuring the width of these rings to determine characteristics of past climates.

这看似简单：每轮代表一年，较宽年轮通常意味着更佳生长条件——充足降水、适宜温度等。

This might seem simple: each ring represents one year, and wider rings generally mean better growing conditions-plentiful rainfall, moderate temperatures, and so forth.

但特定树木的季节性生长除气候外还受其他因素影响。

But the seasonal growth of a particular tree is affected by factors other than the weather.

Trees vary, one from another, just like people do.

每棵树的基因构成独一无二，因此某些个体生长速度可能更快。

The genetic makeup of each individual tree is unique, so one particular tree may grow a bit more quickly than another.

Highly local conditions can also change over time.

不难看到，当树木周边土壤遭侵蚀，其根系必受影响进而限制生长，至少待环境稳定方能恢复。

It is easy enough to see that if part of the soil near a tree has been eroded, this will impact the tree’s root system and limit its growth, at least until the situation stabilizes.

昆虫侵扰可能对某山谷树木造成的影响远超十英里外同种树木。

Then again, an infestation of insects may affect a tree in one valley more than the same type of tree ten miles away.

当邻近参天古木倾倒，某棵树可能突然获得更充足光照。

Or one tree may suddenly start to get a lot more sunlight when an old, big tree in the neighborhood finally falls.

此类因素导致个体样本间存在显著差异，这意味着研究人员需对同一时期同一区域同树种的多个样本进行均值计算。

These kinds of factors produce significant variations among individual specimens, and that fact means that researchers need to average together samples from many specimens of a single tree species in one region over the same time period.

有年轮学家认为，获取当地25-30份年轮记录的平均值是克服个体变异性的必要前提。

Some dendrochronologists think that measuring an average of twenty-five to thirty tree-ring records in a locale is an essential first step in getting around the problem of individual variability.

虽然某些时期在特定区域获取30份样本并非难事，但年代越久远的木材样本，其获取可能性显然会持续降低。

While it may be easy enough to find thirty samples in some locations for particular periods, it obviously becomes less and less likely the more ancient the wood samples are.

What is the primary focus of the passage?

Why does the author provide the information that “if part of the soil near a tree has been eroded, this will impact the tree's root system and limit its growth, at least until the situation stabilizes”?

Which of the following can be inferred from the passage about a tree that “may suddenly start to get a lot more sunlight when an old, big tree in the neighborhood finally falls”?

The word “essential” in the passage is closest in meaning to

According to paragraph 1, how do dendrochronologists deal with the problem of individual tree variability?

The Science of Dendrochronology Dendrochronology is the technique of counting tree rings to determine a tree’s age and measuring the width of these rings to determine characteristics of past climates. This might seem simple: each ring represents one year, and wider rings generally mean better growing conditions-plentiful rainfall, moderate temperatures, and so forth. But the seasonal growth of a particular tree is affected by factors other than the weather. Trees vary, one from another, just like people do. The genetic makeup of each individual tree is unique, so one particular tree may grow a bit more quickly than another. Highly local conditions can also change over time. It is easy enough to see that if part of the soil near a tree has been eroded, this will impact the tree’s root system and limit its growth, at least until the situation stabilizes. Then again, an infestation of insects may affect a tree in one valley more than the same type of tree ten miles away. Or one tree may suddenly start to get a lot more sunlight when an old, big tree in the neighborhood finally falls. These kinds of factors produce significant variations among individual specimens, and that fact means that researchers need to average together samples from many specimens of a single tree species in one region over the same time period. Some dendrochronologists think that measuring an average of twenty-five to thirty tree-ring records in a locale is an essential first step in getting around the problem of individual variability. While it may be easy enough to find thirty samples in some locations for particular periods, it obviously becomes less and less likely the more ancient the wood samples are.