absurd

How: absolutely, completely, clearly, faintly, manifestly, obviously, patently, quite, rather, slightly, somewhat, utterly, wonderfully
Verbs: be, become, find, look, seem, sound
近/反义词: asinine, foolish, ludicrous, impossible, nonsensical, ridiculous, preposterous, silly, stupid, unbelievable; reasonable, sound

In logic, reductio ad absurdum (Latin for 'reduction to absurdity') is the form of argument that attempts to establish a claim by showing that the opposite scenario would lead to absurdity or contradiction. It can be used to disprove a statement by showing that it would inevitably lead to a ridiculous, absurd, or impractical conclusion, or to prove a statement by showing that if it were false, then the result would be absurd or impossible. Traced back to classical Greek philosophy in Aristotle's Prior Analytics, this technique has been used throughout history in both formal mathematical and philosophical reasoning, as well as in debate.

The "absurd" conclusion of a reductio ad absurdum argument can take a range of forms, as these examples show:

The Earth cannot be flat; otherwise, we would find people falling off the edge.
There is no smallest positive rational number because, if there were, then it could be divided by two to get a smaller one.
The first example argues that denial of the premise would result in a ridiculous conclusion, against the evidence of our senses. The second example is a mathematical proof by contradiction (also known as an indirect proof), which argues that the denial of the premise would result in a logical contradiction (there is a "smallest" number and yet there is a number smaller than it).

六级/考研单词: logic, absurd, scenario, contradict, inevitable, ridicule, trace, classic, mathematics, rational

abundant

近/反义词: ample, bountiful, copious, luxuriant, plentiful, plenteous, profuse, teeming; deficient, insufficient, rare, scarce, scant, short

In ecology, local abundance is the relative representation of a species in a particular ecosystem. It is usually measured as the number of individuals found per sample. The ratio of abundance of one species to one or multiple other species living in an ecosystem is referred to as relative species abundances. Both indicators are relevant for computing biodiversity.

A variety of sampling methods are used to measure abundance. For larger animals, these may include spotlight counts, track counts and roadkill counts, as well as presence at monitoring stations. In many plant communities the abundances of plant species are measured by plant cover, 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. It is common for the distribution of species to be skewed so that a few species take up the bulk of individuals collected.

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

In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic weight listed for the element in the periodic table. 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).

The mole fraction is also called the amount fraction. It is identical to the number fraction, which is defined as the number of molecules of a constituent 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 x. mole应该是molecules的abbreviation，和摩尔人(Moors)无关。

六级/考研单词: ecology, abundant, ecosystem, multiple, compute, spotlight, plot, bulk, physics, planet, fraction, molecule, constituent, denote, abbreviation