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自然科學 大學

求解答案是否正確

Multiple-choice questions: (70 points) write the letter of statement that is not true: 1. A.B.U The Drude Model: (a) It is a classical approach using concepts from the kinetic theory of gases. (b) A relaxation-time approximation is used where the probability of collision is l/t. (c) No forces act on the electrons in between collisions. (d) It predicts accurately the electronic heat capacity of metals. 2. The Sommerfeld Model: (a) The crystal potential is replaced by an average Coulomb potential. (b) The separation of states is so close that a continuum model can be applied. (c) The electrons are highly localized due to a strong crystal potential. (Q) The energy of the highest occupied state at 0 K is the Fermi energy. 3. Density of states in k-space, N(k): (a) N(k) is determined by the boundary value conditions. (b) For lattices in any dimensions, N(k) is constant in k-space. (C) N(k) depends on the direction and magnitude of k. (d) It is directly proportional to the volume of the crystal. E影響, c 4. The Fermi surface of a metal: (a) is responsible for many of the transport properties of the metal, (b) depends on the nature of the chemical bonds, (c) is always a sphere, (d) can involve mixing of electron orbitals. ✓ 5. The conductivity of a material () increases with the mobility of its carriers, (b) increases with the density of carriers, (C) it is inversely proportional to the energy gap. cogu changes with temperature. 6. BID Plasmons: (a) They are an important characteristic of the Sommerfeld electron gas model. (b) Plasmons occur spontaneously in metals. (c) They are related to charge density oscillations. (d) The Plasmon energy is typically of the order of 10 eV. The Fermi energy Ef in intrinsic semiconductors 8) is usually close to y E, at OK (b) it ACiD. can increase or decrease with temperature depending on the ratio of hole and electron effective masses, (c) it represents the point at which the probability of occupation is 12, even though there may not been any states with that energy, (d) its value relative to the electronic bands must remain unaffected in the presence of defects or interfaces.

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英文 高中

請問14題為什麼是a?印象中while後面應接ving?

(B) Have you ever pondered how you got your name? Few of us would answer "yes" since we 11_our naming traditions that we usually take them for granted. Actually, naming traditions vary from country to country. Some distinct differences 12__ customs can be easily spotted between Chinese culture and Western cultures. First of all, Chinese people tend to keep their family names from generation to generation while in many Western countries surnames often change, 13 is the reason why there is a wider range of them. Furthermore, Chinese and Western people show respect for their elders and ancestors in different ways. 14 do not pass on their given names, 14 the latter sometimes name their children after an ancestor. In cultures 15 family links are indicated in names, some unique rules exist. In Iceland, a person's last name usually comes directly from the first name of the father. For instance, a boy named Erik 16 a father named Lars would be named Erik Larsson. Lars's daughter, Kristin, would go by the name of Kristin Larsdottir. 17_, the vast majority of Icelandic names end in either "son" or "dottir." For the Yami people of Taiwan, the son does not take the name of the father, 18_, the father changes his name 18_ the birth of his first son. Additionally, the boy's grandfather's name is changed too. A 11. (A) are so used to (B) used to (C) got so used to (D) use to 12. (A) regards (B) regarding names (C) regarding naming (D) regards naming (B) which (C) it (D) what (A) The former; while B) The first; but (C) The former; however D) The first; yet nes CD B 13. JA) that AC

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