[题目]在家鼠中短尾(T)对正常尾(t)为显性.一只短尾鼠与一只正常鼠交配.后代中正常尾与短尾比例相同,而短尾类型相互交配.子代中有一类型死亡.能存活的短尾与正常尾之比为2∶1.则不能存活类型的遗传因子组成可能是 ( )A．TT B．Tt C．tt D．TT或Tt 题目和参考答案——青夏教育精英家教网—

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【题目】在家鼠中短尾（T）对正常尾（t）为显性。一只短尾鼠与一只正常鼠交配，后代中正常尾与短尾比例相同；而短尾类型相互交配，子代中有一类型死亡，能存活的短尾与正常尾之比为2∶1，则不能存活类型的遗传因子组成可能是（）

A．TT B．Tt C．tt D．TT或Tt

【答案】A

【解析】根据一只短尾鼠与一只正常鼠交配，后代中正常尾与短尾比例相同，即后代正常尾∶短尾=1∶1可知短尾亲本的遗传因子组成为Tt，子代正常尾遗传因子组成为tt，短尾遗传因子组成为Tt。又因为短尾类型相交配，子代中有一类型死亡，能存活的短尾与正常尾之比为2∶1，如果亲本有纯合子，则后代不会出现性状分离，所以该实验中亲本短尾遗传因子组成全为Tt，他们之间杂交的后代遗传因子组成比例应为TT∶Tt∶tt=1∶2∶1，由于第二代杂交结果是短尾与正常之比是2∶1，则可以推出不能存活类型的遗传因子组成为TT。

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(2)气体A中肯定不存在的气体是________，理由是__________。

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【题目】语法填空

阅读下面材料，在空白处填入1个适当的单词或括号内单词的正确形式。

W: So Mr. Brown, this is your bed, and as you can see, there are three other beds in the ward(病房). Have you __1__(get) everything you need?

M: Yes, nurse, I think 2 . I followed the hospital’s advice, and I’ve only brought a few 3 (belong) with me.

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M: I see. What other rules are there?

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【题目】书面表达

体裁	话题
提纲作文，记叙文	校音乐周的情况

请根据以下中文提示，用英语写一篇短文，介绍你校在3月第一周举行音乐周的情况。内容如下：

1. 每个班级都表演了节目，有唱歌、跳舞、短剧等，有的班级还用英语进行了表演。

2. 我们邀请了一位著名的钢琴家来表演，并进行了有关钢琴知识的讲座。

3. 学校举办了音乐知识竞赛。

注意：

1. 词数：100词左右。

2. 参考词汇：竞赛：contest

_________________________________________________________________________________________

【题目】A

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Beijing, China

Beijing is the second largest city in China and serves as the capital. The city is so old, in fact, that almost every building has some sort of cultural or historic features — no matter how small. Getting around the city you’ll find yourself faced with amazing temples (寺庙), the largest palaces in the world, and many works of art that leave you breathless.

Siem Reap, Cambodia(柬埔寨)

Siem Reap is the capital city of Siem Reap Province in northwestern Cambodia. Siem Reap has a lot of French and Chinesestyle architecture. In the city, there are traditional dance performances, silk farms, fishing villages and a bird sanctuary (保护区) near the Tonle Sap Lake. Siem Reap today, being a popular tourist attraction, has a large number of hotels and restaurants.

Kathmandu, Nepal(尼泊尔)

Situated in the heart of the Himalayans, Kathmandu, the largest city and capital of Nepal, is considered to be one of the most outstanding cities in the world today. The shopping districts are world famous and the hotels in Kathmandu are among the most comfortable in the world.

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The city of Kyoto served as the capital of Japan from 794 to 1868. No longer the capital, it is known for being the seventh largest city in Japan. Kyoto was destroyed throughout history by fires and war. But now the city is home to more than 1.4 million people, and it presents a modern face to the rest of the world.

Every city throughout Asia has a story of its own. It’s up to you to explore them all and find out exactly what each one has to offer. Enjoy!

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B. to compare some tourist cities in Asia

C. to tell readers not to visit European cities

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【题目】A

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C．live in Milton and go to Milton School

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