在act阅读考试自然科学的文章中，最常考的话题有三个，分别是：

　　animal，plant，和astronomy

　　这里给大家列出了这三个话题中最常考的高频词汇。

　　Plant

　　Bark：tough protective covering of the woody stems

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　　The giant redwood has cinnamon-coloured bark, which may grow to a massive 18 in/45 cm thick.

　　Grove: a small growth of trees

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　　Today they are a truly relict species, occurring only in isolated groves on the western slopes of the Sierra Nevada in California.

　　Pollen: a fine powder produced by flowers

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　　Young workers of five days of age or more who have been feeding heavily on pollen produce for the larvae a protein-rich substance called bee milk or royal jelly.

　　Sap: a watery solution of sugars, salts, and minerals that circulates through a plant

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　　They are large—and noisy一for insects that feast on sap: the smallest are 10 millimeters (just under half an inch) long, the largest 100 millimeters (four inches)

　　Stem: a slender structure that supports a plant

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　　Female cicadas lay their eggs in the stems of plants or in trees.

　　Trunk: the main stem of a tree

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　　The largest trunk of any redwood is found on a tree in Alder Creek, which averages 53 ft/16 m around its base.

　　Animal

　　Abdomen: belly

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　　A click from the rib of a tymbal produces high sound pressures within the cicada's abdomen.

　　Anatomy: the branch of morphology that deals with the structure of animals

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　　Neanderthals started thinking about these people in terms of their behavior and not just their anatomy.

　　Burrow: a hole in the ground made by an animal for shelter

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　　Later, the newly hatched young drop to the ground and burrow in search of plant roots to tap.

　　Corpse: the dead body

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　　They carry the corpses of other bees a distance from the hive and drop them to the ground.

　　Demise: death

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　　But the best illustration of dinosaurian capability may well be the fact most cited against them their demise.

　　Ectothermy

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　　Skeptics counter that, “ectothermy” the proper label for cold bloodedness, was the logical strategy for dinosaurs living in the Mesozoic Era.

　　Endothermy

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　　For some, endothermy, the scientific name for warm bloodedness, is the only way to explain the dinosaurs' evolutionary success.

　　Gland: an organ of the body which produces a substance that the body needs

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　　At the end of ten days the glands on the head of the nurse begin to shrink; she can no longer produce royal jelly.

　　Herd: a group of animals of one kind that live and feed together

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　　Did some dinosaurs live in herds?

　　Intruder: a person who goes into a place where they are not supposed to be

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　　Others guard the entrance to the hive; they use their stingers to attack intruders, including honey-stealing bees from other hives.

　　Larva/Larvae: the immature free-living form of life

　　Eels hatch in the Sargasso as larvae and are carried by the ocean currents to either Europe or the United States, a journey that can cover thousands of miles and take years.

　　Metabolism

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　　Deep-diving submarines found “cryptoendolithic” organisms whose metabolism is driven by heat from a geothermal source.

　　Microbe

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　　Some researchers argue that many of these microbes belong to a distinct and previously unrecognized branch of life.

　　Organ：a fully differentiated structural and functional unit in an animal that is specialized for some particular function

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　　Bluefin tuna thrive in waters as cold as 40 degrees Fahrenheit and as warm as 75 degrees Fahrenheit but unlike swordfish, they do not possess organs whose chief function is to produce heat. Instead they retain the heat they: generate swimming.

　　Organism

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　　Deep-diving submarines found “cryptoendolithic” organisms whose metabolism is driven by heat from a geothermal source.

　　Pupil

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　　Their pupils will expand and turn blue.

　　Skull: the bony skeleton of the head of vertebrates

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　　They could be guided by internal com- 85 passes of magnetite chips embedded in their skulls; by the warmth, salinity, or motion of the current

　　Tissue: the material forming animal or plant cells

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　　These elegant patterns form when growing bone meets and meshes with connective tissue, capturing blood vessels in dense, woven structure called Haversian canals.

　　Vessel: a vein in the body

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　　These elegant patterns form when growing bone meets and meshes with connective tissue, capturing blood vessels in dense, woven structure called Haversian canals.

　　Sentience: ['sen??ns] n. 知觉 the faculty through which the external world is apprehended

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　　What “are you seeing when you see sentience in a creature?”

　　Creature: [?krit??] n. 生物 a living organism characterized by voluntary movement

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　　What “are you seeing when you see sentience in a creature?”

　　Neuron：[?n?rɑ:n] n. 神经细胞 a cell that is specialized to conduct nerve impulses

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　　But there are no neurons or synapses in the human brain that aren’t also in animals.

　　Stimulate: [?st?mj??let] v. 刺激 cause to be alert and energetic

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　　At Central Park the exercise with the log and snack goes by the grander name of “animal enrichment” and is intended to stimulate the bears’ minds as well as their appetites.

　　Chew: to bite the food several times before swallowing it

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　　Workers roll the wax up away from their abdomens with the legs, and chew and soften it with saliva.

　　Digest

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　　They will never eat again, and their digestive systems will atrophy.

　　Feast: eat

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　　They are large—and noisy一for insects that feast on sap: the smallest are 10 millimeters (just under half an inch) long, the largest 100 millimeters (four inches).

　　Forage: the act of searching for food and provisions

　　Plummet: decline dramatically

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　　Warm venous blood flowing away from muscles heats cold blood coming in through the arteries, enabling bluefin to retain 98 percent of their body heat, giving them free rein to forage in cold waters and to dip in and out of the Gulf Stream, where sea temperatures plummet as much as 27 degrees Fahrenheit across one nautical mile.

　　Astronomy

　　Crater: a bowl-shaped geological formation at the top of a volcano

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　　“The basic idea,” J Melosh says, “is that an impact doesn’t just open a crater. With high velocities, the projectile vaporizes and expands into the atmosphere.”

　　Lava：rock that in its molten form (as magma) issues from volcanos

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　　One of the first Martian rocks to be analyzed by the rover from NASA’s Pathfinder spacecraft appears to be andesite, a type of lava found in the Columbia Basin, an area some view as an apt geological analog to Mars.

　　Stellar: being or relating to or resembling or emanating from stars

　　But only one person in ten thousand is an astronomer. What possible relevance could these stellar explosions thousands of light years away have to all the others, whose business lies purely on or near the Earth’s surface?