题干

《九章算术》是我国古代内容极为丰富的数学名著,书中有如下问题:“今有垣厚五尺,两鼠对穿.大鼠日一尺,小鼠亦日一尺.大鼠日自倍,小鼠日自半.问几何日相逢?各穿几何?”,翻译成今天的话是:一只大鼠和一只小鼠分别从的墙两侧面对面打洞,已知第一天两鼠都打了一尺长的洞,以后大鼠每天打的洞长是前一天的2倍,小鼠每天打的洞长是前一天的一半,已知墙厚五尺,问两鼠几天后相见?相见时各打了几尺长的洞?设两鼠x 天后相遇(假设两鼠每天的速度是匀速的),则x=(   )

A:2118

B:2117

C:2217

D:219

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C

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                                                                                      Pronunciation Tips

           These English pronunciation tips will help you get the most out of your Pronunciation Power program.

★ ____

    For example, “threw” and “through”, although spelled differently, are pronounced the same. Also, identical(相同的)letters or letter clusters(字母组合) in words do not always produce the same sound. For example, the “ough” in “though” and “through” represents a different sound in each word.____

★ Imagine a sound in your mindbefore you say it.

    Try to visualize(想象))thepositioning of your mouth and face.____

★ Listen to and try to imitate thePronunciation Power instructor.

    In addition to listening for specific sounds, pay attention to pauses, the intonation(语调) of the instructor's voice and patterns of emphasis.____

★ The English language has manydifferent dialects, and words can be pronounced differently.

    It is important, however, that you pronounce words clearly to ensure effective communication.

★ Finally, the Pronunciation Powerprogram is a tool to help you.

    But you must practice what you are learning! Remember that you are teaching your mouth a new way to move. You are building muscles that you do not use in your own language.____Use the program to exercise yourmouth a little bit each day.

a. Read these words over and over againand try to learn them by heart.

b. This can be just as important as the pronunciation of sounds.

c. Learn to practice what you hear, notwhat you see.

d. So you should force yourself to dowhat you really don't like to do.

e. Do not confuse pronunciation of words with their spelling!

f. It is like going to the gym andexercising your body.

g. Think about how you are going to make the sound.