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问题 多项选择题

有线电视信号经过同轴电缆传输，为保证高低端频道的信号电平均衡，常用以下斜率校正方法（）。

A、在干线中串入斜率均衡器

B、利用具有斜率均衡作用的干线放大器进行斜率校正

C、利用分波器把高频段的电视信号分离，再经混合器混合

D、利用具有自动斜率增益的放大器和导频信号发生器

E、以上皆不是

答案

参考答案：A, B, C, D

判断题

钢是含碳量在0.0218％~2.11％之间的铁碳合金。
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问答题

The teaching of English as a second language (ESL) in schools has had a history of conflicting arguments, interesting innovations and some very positive methodological changes. To understand the present situation, it is necessary to consider the past and the wider educational context which has a hearing on it.

Until quite recently, approaches to ESL work have been ply influenced by methods developed to teach English as a foreign language to older learners. These methods placed much emphasis on drills, exercises and remedial programs that focus on language in abstraction. 46) The prescriptive nature of such methods and the demands they made on the teacher’s time developed the belief that ESL work could be tackled only by the specialist ESL teacher working with small groups of children. Such an approach does not fit comfortably into current notions of learning and teaching in the primary school, nor does it sufficiently equip ESL learners in the secondary school to benefit from normal schooling. 47) In prescribing what language is to be taught, it has ignored what children bring to the learning task and the choices they make about how and what they want to learn. Furthermore, the location and organization of language provision did not measure up to the demand. 48)The language centers and English language services all contributed to providing special and concentrated teaching of English as a second language in small groups, varying in size from four or five to fifteen. Whatever the pattern of provision, the main aim was to give pupils sufficient English to enable them to join normal schools as quickly as possible. The success of such special provision depended very much on the close and constant liaison of language teachers with the subject teachers and the class teachers and on the continuity of learning experiences provided by them. 49)One of the important disadvantages of language centers and withdrawal groups was that ESL children were being taught away from those English -speakers who provide the most powerful models, i. e. their peer group. Peer-group interaction is an important element in any learning situation, but its particular strengths in a classroom with ESL learners cannot be overemphasized.

50) The separation of second language learners from the mainstream classroom cannot easily be justified on educational grounds, since in practice it leads to both their curriculum and language learning being impoverished.

Notes: context 环境。bear on 对......有影响，关系到...... 。例如：I don’t see how this bears on the matter. (我不明白这一点与那些事的关系。)liaison n. 联结。liaison of A with A与B之间的联系。

47) In prescribing what language is to be taught, it has ignored what children bring to the learning task and the choices they make about how and what they want to learn.
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