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问题 选择题

已知X、Y、Z三种元素组成的化合物是离子晶体，其晶胞如图所示，则下面表示该化合物的化学式正确的是

[ ]

A．ZXY3

B．ZX2Y6

C．ZX4Y8

D．ZX8Y12

答案

答案：A

单项选择题 A1/A2型题

HLAⅡ类分子多态性部位是（）.

A.肽结合区

B.跨膜区

C.Ig样区

D.胞质区

E.β2肽链区
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句型转换

按要求改写下列句子。

1. Have you looked in the classroom? (做肯定回答)

    ______, I ______.

2. Jenny is at the computer. (就划线部分提问)

    ______ ______ Jenny?

3. It's a quarter after three. (改为同义句)

    It's a ______ ______ ______.

4. His father has been to America. (就划线部分提问)

    ______ ______ his father ______?

5. She has finished her homework. (改为一般疑问句)

    ______ she ______ her homework?
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