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在甲类、乙类和甲乙类三种类型的功率放大电路中，实际的小功率低频功率放大电路中，是采用的______类放大电路。

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P型杂质半导体中，多数载流子是( )

A. 自由电子
B. 空穴
C. 正离子
D. 负离子

Proofread the given passage on ANSWER SHEET TWO as instructed. For a wrong word, underline the wrong word and write the correct one in the blank provided at the end of the line. For a missing word, mark the position of the missing word with a "∧" sign and write the word you believe to be missing in the blank provided at the end of the line. For an unnecessary word, cross the unnecessary word with a slash "—" and put the word in the blank provided at the end of the line. Like all animal species, plant species must spread their offspring to suitable areaswhere they can grow and pass on their parent’s genes. Young animals generally spread by (1) walking or flying. Because plants don’t have that ability, they may somehow hitchhike. (2) Some plant seeds scatter by blowing in the wind or floating on water. Many other plantspecies, though, trick an animal into carrying their seeds. How do they do They enclosethem within a tasty fruit and advertise the fruit’ s ripeness by its color or smell. The hungryanimal collects and swallows the fruit, walks or flies off, but later spits out the seeds some- (3) where far from its parent tree. Seeds can thereby be carried thousands of mi]es. It may (4) surprise you to learn that plant seeds can resist digestion. In fact, some seeds actuallyrequire passage through an animal’ s body before they can grow. Wild strawberries offer agood example of hitchhiking tactic. When strawberry seeds are still young and not yet (5) ready to be planted, the surrounding fruit is green, sour, and hard. When the seeds final (6) mature, the berries turn red, sweet, and tender. The change in the berries’ color serves as asignal to birds which then eat the strawberries, fly off, and eventually spit out the seeds.Naturally, strawberry plants doesn’t set out with a conscious intent of attracting birds only (7) when their seeds were ready to be dispersed away. Nor did birds set out with the intent of (8) planting strawberries. Rather, strawberry plants evolved through natural selection. Thesweeter and ruder the final strawberry, the more birds spread its ripe seeds; the greener and (9) more sour the young strawberry, the birds destroyed the seeds by eating berries before the (10) seeds were ready.

晶体三极管处在截止状态时是( )

A. C结反偏E结反偏
B. C结正偏E结正偏
C结正偏E结反偏
D. C结反偏E结正偏

SECTION A In this section you will hear a mini. lecture. You will hear the lecture ONCE ONLY. While listening to the lecture, take notes on the important points. Your notes will not be marked, but you will need them to complete a gap-filling task on ANSWER SHEET ONE after the mini-lecture. Use the blank paper fornote-taking. Now listen to the mini. lecture. Humanities DisciplinesIn many people’s eyes, the humanities disciplines seem to be dying out.However, actually, students continue to enroll in humanities courses andlots of scholarship is still published. The humanities disciplines feeldislocated, because they appear to have lost their (1). (1) And the most important one is exactly what those roots were.The history of higher education in the United States since (2) can (2) be divided into 2 periods.Ⅰ. The first period (1945—1975): A period of (3)and known in the literature on American (3) education as the Golden Age, during which the composition of the highereducation system changed not too much, but the size of the system(4) dramatically. (4) This expansion includes three factors: 1) The baby boom: a period of record (5)that followed a period of (5) record low blah rates—the (6)and the Second World War; (6) 2) The relatively high domestic economic growth rate after (7); (7) 3) The Cold War: American university had been drawn into the business ofgovernment-related (8)research during the Second World War. (8) IL The second period (1975—present) A period of (9), during which the size of the system has grown at a much (9) more (10)pace, and the composition has changed dramatically. (10)