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问题 解答题
化简：
sin(π-α)sin(3π-α)+sin(-α-π)sin(α-2π)
sin(4π-α)sin(5π+α)
．
答案

sin(π-α)sin(3π-α)+sin(-α-π)sin(α-2π)
sin(4π-α)sin(5π+α)

=

sinα•sinα+sinα•sinα
-sinα•(-sinα)

=2．

选择题

某同学用低倍镜观察到根尖分生区细胞的清晰物像，这时如果转动转换器改用高倍镜观察，下列情况一般不会出现的是（　　）

A．视野内的细胞变少了，变大了

B．视野变亮了

C．物像变模糊了

D．物像不在视野正中央
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问答题

Oxford When language learners arrive in Oxford, many ask where the university is, thinking that they will be shown just one building. It’s up to their teachers to explain that Oxford university is made up of a collection of many different colleges and institutions, each with its own history and characteristics. There are many other surprises that learners discover about the city and its university. Katie Jennings is a social organizer at King’s St Joseph’s Hall in East Oxford, and it is her job to organize activities for learners outside of lesson time. She says many learners are surprised to discover that Oxford is a home to a wide variety of nationalities and ethnic groups, and one of the most popular social events is a night out at one of the town’s Latin American dance clubs. After a day spent learning English and absorbing the ancient atmosphere of the university, learners can samba the night away. The city also has a thriving Asian community, and the sight of women in saris is as common in Oxford’s streets as academics in gowns and mortarboards. There is also a mouth-watering selection of Asian restaurants serving curries, as well as shops stocked with exotic vegetables and fruits. The city has attracted such a diverse population not only because of the university, but also because it is an important industrial centre which is known for car manufacturing among other things. In spite of large industrial areas, the old of the city centre has remained surprisingly intact. Carmel Engin, who teaches at the Lake School, says many learners are surprised to find that the city is free from the usual high-rise modem buildings. "From the centre of Oxford, you can see green hills in the distance, and this will make learners deeply feel that they are in a small, friendly town, but not just another modem metropolis. Some learners will be tempted to explore those green hills—Oxford is surrounded by some of the most beautiful countryside in southem England—but, as Engin admits, with so much to do and see in the city, few learners find the time to explore its surroundings. Oxford has developed some imaginative initiatives for language learners. One is a local radio station which broadcasts news and provides information for learners. They can visit the station to get experience in radio production. Or they can meet university students in pubs and clubs or at one of the many campus sports facilities which are open to language learners.
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