In ecology [生态学], local abundance is the relative representation of a species in a particular ecosystem [生态系统]. It is usually measured as the number of individuals [个体] found per sample [样本。本句中生态系统]. The ratio of abundance of one species [物种] to one or multiple other species living in an ecosystem is referred to as relative species abundances. Both indicators are relevant for computing biodiversity [生物多样性bio+diverse+ity].

species的复数还是species，或者说它没有单数形式。data, datum像英文版的茴香豆的茴字有几种写法。actresses是女演员们。

A variety of sampling [取样本] methods are used to measure abundance. For larger animals, these may include spotlight [像野外有个相机] counts, track [兽痕] counts and roadkill [倒霉] counts, as well as presence at monitoring stations. In many plant communities [团体] the abundances of plant species are measured by plant cover [植被覆盖], i.e. the relative area covered by different plant species in a small plot. Abundance is in simplest terms usually measured by identifying and counting every individual of every species in a given sector [地区]. It is common for the distribution [分布] of species to be skewed [不是screw] so that a few species take up the bulk [大量] of individuals collected [收集的可能只是数据].

Relative species abundance is calculated by dividing the number of species from one group by the total number of species from all groups.

In English, ordinal numbers [序数] are countable, so you need to add 's' to the word: We pronounce 2/3 as two-thirds, 3/4 as three-fourths, and 6/8 as six-eighths. We have special words to talk about fractions that have 2 and 4 on the bottom [分数线的下面，分母, denominator]: We pronounce 1/2 as one-half, 1/4 as one-quarter, and 3/4 as three-quarters. I tought (thought) I taw (saw) 3-22nds before, but I can't assure you. Sylvester the Cat and Tweety Bird are two of the most well known characters in the Looney Tunes and Merrie Melodies stable.

[牛津词典] stable: 马厩/训练学校. actors from the same stable: 在同一处受训的演员。
lock the stable door after the horse has bolted: 亡马锁厩。这马还是像闪电狗波特一样跑出去的。
“见兔而顾犬，未为晚也；亡羊则补牢，未为迟也。”

In physics, natural abundance refers to the abundance of isotopes [同位素] of a chemical element as naturally found on a planet. The relative atomic mass [质量] (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic weight [重量] listed for the element in the periodic table [周期表]. The abundance of an isotope varies from planet to planet, and even from place to place on the Earth, but remains relatively constant in time (on a short-term scale).

相对原子质量是指以一个碳-12原子质量的1/12作为标准，任何一个原子的真实质量跟一个碳-12原子质量的1/12的比值。原子量最早是由英国科学家道尔顿提出来的。他说“同一种元素的原子有相同的重量(weight)，不同元素的原子有不同的重量。”因此atomic weight在中文里翻译成了“原子量”。但是当时由于重量和质量(mass)是相同的概念，因此虽然实际中获得的都是原子的相对质量，但仍然称作原子量。道尔顿和牛顿…… 红脸的窦尔敦盗御马……

The mole fraction [摩尔/克分子分数] is also called the amount fraction. It is identical to the number fraction, which is defined as the number of molecules of a constituent [成分的] N_i divided by the total number of all molecules N_tot. The mole fraction is sometimes denoted by the lowercase Greek letter χ (chi, 卡方检验的卡) instead of a Roman [罗马] x. mole应该是molecules的abbreviation [缩写]，和摩尔人(Moors)无关。