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问题 填空题

如果log2x+log2y=1，则x+2y的最小值是______．

答案

如果log2x+log2y=1，可得 log2 xy=1，x＞0，y＞0，且 xy=2．

则x+2y≥2

x•2y
=4，当且仅当x=2y 时，等号成立．

故答案为 4．

单项选择题

1985年7月成立（），是勘察设计咨询行业全国性社会团体组织

A.中国国际工程咨询协会

B.中国建设监理协会

C.中国勘察设计协会

D.中国设备监理协会
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单项选择题

Are you dreaming of taking a trip on your own Here is some advice on how to make your once-in-a-lifetime journey and how to stay safe when you get there.
Before you begin to look at places, activities and plane tickets, you must set a budget. When you search through the websites about travelling, it can be so easy to add another week here or there, or choose an extra activity. Setting a budget can avoid creating a huge bill, which starts very small.
With so many countries on this planet it is difficult to decide where to go. By narrowing down your search to voluntary work or a relaxing holiday, you can save a lot of time looking through websites.
After deciding where to go, you need to research the country. Find out when each season is. It would be disappointing if you were taking part in an outdoor-based activity and it rained most days. Look into medical information, as you may need certain medicine for certain countries. Above all, make sure you can afford to go to this country and take part in the activities you have dreamt about. Don’t raise your hopes too high before you know for certain it is within your budget.
By carrying a credit (信用) card with you at all times it is possible to stop yourself getting lost. Mobile phones are very important as well. However, do not depend completely on them, since electronic machines can break without warning. Therefore, always carry a list of emergency (紧急情况) phone numbers, names and addresses. Finally, learn a little of the language. Do not expect that the people there speak your own language. After all, you are in their country.

From the text, we can know that ______.

A．travelling in a foreign country costs a lot
B．deciding on where to go is an easy job
C．a volunteer can help you choose where to go
D．you need to know what the weather of the county you’ll travel is like
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