更多"Atoms, the basic building blocks of"的相关试题:
[单项选择]Atoms, the basic building blocks of matter, are made of three basic components: protons, neutrons and electrons. The protons and neutrons cluster together to form the nucleus, the central part of the atom, and the electrons orbit about the nucleus. Protons and electrons both carry an electrical charge(电荷). The charges they carry are opposite to each other; protons carry a positive electrical charge while electrons carry a negative electrical charge. Neutrons carry no charge at all.
Electricity is the movement of charged particles, usually electrons, from one place to another. Materials that electricity can move through easily are called conductors. Most metals, such as iron, copper and aluminum, are good conductors of electricity. Other materials, such as rubber, wood and glass, block the flow of electricity. Materials which prevent the flow of electricity are called insulators (绝缘体). Electrical cords are usually made with both conductors and insulators. Electricity flows throug
A. rubber inside and copper outside
B. iron inside and copper outside
C. rubber inside and glass outside
D. copper inside and glass outside
[单项选择]Galaxies are the major’ building blocks Of the universe: A galaxy is giant family of many millions of stars, and it is held together by its own gravitational field. Most of the material universe is organized into galaxies of stars together with gas and dust.
There are three main types of galaxy: spiral, elliptical, and irregular. The Milky Way is a spiral galaxy, a flattish disc of stars with two spiral arms emerging from its central nucleus. About one-quarter of all galaxies have this shape. Spiral galaxies are well supplied with the interstellar gas in which new stars form: as the rotating spiral pattern sweeps around the galaxy it compresses gas and dust, triggering the formation of bright young stars. The elliptical galaxies have a symmetrical elliptical or spheroidal shape with no obvious structure. Most of their member stars are very old and since ellipticals are devoid of interstellar gas, no new stars are forming in them. The biggest and brightest galaxies in the universe
A. The Milky Way.
B. Major categories of galaxies.
C. How elliptical galaxies are formed.
D. Differences between irregular and spiral galaxies.
[单项选择]A. It doesn’t matter. B. I caught a cold. C. It matters a lot. D. I don’t like it.
[单项选择]
Particles that radiate from decaying radon atoms can destroy the living cells they strike and increase the likelihood that those cells will later become cancerous. Researchers have now directly demonstrated that neighboring cells not suffering direct hits can be harmed, too. They’ve also taken a step toward showing how this type of radiation, called alpha particles, indirectly hurts those bystanders.
Radon derives from the decay of uranium and seeps naturally into the air from the ground. It’s the primary environmental source of alpha particles, which contribute to cancer risk by causing aberrations in DNA. Alpha particles from inhaled radon are second only to smoking as a cause of lung cancer.
Because a person’s exposure to alpha particles typically is low, researchers have had to estimate public health threats from radon by guess from the effects of higher dose of alpha radiation. Such data comes primarily from studies of survivors of the atomi
A. the experiment done by researchers
B. that uranium is the key killer of neighboring cells
C. that cell-to-cell interaction can make up for the hurt cells
D. that bystander cells can be indirectly damaged by alpha particles
[单项选择]Atoms that (having) different atomic (numbers) generally (behave) (differently).（）
A. having
B. numbers
C. behave
D. differently
[单项选择]It is a must to preface any discussion of atoms by paying homage to Democritus, an Ionian philosopher of the fifth century B. C., the earliest known proponent of an atomic theory. Though Democritus’ idea were in many ways strikingly modern and were promulgated (传播) by his more celebrated successor Epicurus, his theory never gained wide acceptance in Greek thought. It had largely been forgotten by the time of the late Renaissance rebirth of science. While the dramatic rise of the atomic theory over the last century and a half deems to have vindicated (证明……正确) Democritus, only the Greek name atom ("indivisible") remains to establish his claim as the father of the theory.
Nonetheless, Democritus’ thinking contained the seed of the idea that has dominated the twentieth-century physical thought. He was one of the first to perceive that nature on a sufficiently small scale might be qualitatively different in a striking way from the world of our ordinary experience. And he was the firs
A. The theory was finally empirically proved in the 19th century.
B. The theory was the basis of modern physics.
C. The theory was accepted by no physical scientists till the 20th century.
D. The theory was accepted by no chemical scientists till the 20th century.
