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发布时间：2006-06-22 13:29     点击：

    (D) generally in agreement with Vinaver's comparisons between Malory and modern novelists

    (E) originally skeptical about Vinaver's early conclusions with respect to modern novels

    We can distinguish three different realms of matter, three levels on the quantum ladder. The first is the atomic realm, which includes the world of atoms, their interactions, and the structures that are formed by them, such as molecules, liquids and solids, and gases and plas- mas. This realm includes all the phenomena of atomic physics, chemistry, and, in a certain sense, biology. The energy exchanges taking place in this realm are of a rela- tively low order. If these exchanges are below one elec- tron volt, such as in the collisions between molecules of the air in a room, then atoms and molecules can be regarded as elementary particles. That is, they have "conditional elementarity" because they keep their iden- tity and do not change in any collisions or in other pro- cesses at these low energy exchanges. If one goes to higher energy exchanges, say 104 electron volts, then atoms and molecules will decompose into nuclei and electrons; at this level, the latter particles must be consi- dered as elementary. We find examples of structures and processes of this first rung of the quantum ladder on Earth, on planets, and on the surfaces of stars.

    21. the primary topic of the passage is which of the following?

    (A) The interaction of the realms on the quantum ladder

    (B) Atomic structures found on Earth, on other planets, and on the surfaces of stars

    (C) Levels of energy that are released in nuclear reactions on Earth and in stars

    (D) Particles and processes found in the atomic, nuclear, and subnuclear realms

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