下图为某家族甲、乙两种遗传病的系谱图。甲遗传病由一对等位基因(A,a)控制,乙遗传病

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问题:

下图为某家族甲、乙两种遗传病的系谱图。甲遗传病由一对等位基因(A,a)控制,乙遗传病由另一对等位基因(B,b)控制,这两对等位基因独立遗传。已知III-4携带甲遗传病的致病基因,但不携带乙遗传病的致病基因。回答问题:

科学家从患者体细胞中提取出b基因进行研究,并利用()技术对b基因进行扩增。

考点:高中生物人类遗传病人类遗传病题库
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在 SQL 的 SELECT 查询结果中,消除重复记录的方法是______。

A.通过指定主关系键

B.通过指定惟一索引

C.用 DISTINCT 子句

D.使用 HAVING 子句

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紫花地丁()

A.草酸钙砂晶和方晶

B.草酸钙针晶及片状结晶

C.草酸钙簇晶

D.草酸钙砂晶及小方晶

E.草酸钙棱晶及针晶

题型:填空题 案例分析题

最好置于密闭容器中,避免与空气接触的是()

A.含生物碱类中药

B.含苷类中药

C.含油脂类中药

D.含植物色素类中药

E.含挥发油类中药

题型:填空题 案例分析题

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.

题型:填空题 案例分析题

城市轨道交通信号系统通常包括两大部分,分别为()和()。

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