初中生英语演讲三分钟（精选3篇）
i have the answer to a question that we've all asked. the question is, why is it that the letter x represents the unknown? now i know we learned that in math class, but now it's everywhere in the culture -- the x prize, the x-files, project x, tedx. where'd that come from?
about six years ago i decided that i would learn arabic, which turns out to be a supremely logical language. to write a word or a phrase or a sentence in arabic is like crafting an equation, because every part is extremely precise and carries a lot of information. that's one of the reasons so much of what we've come to think of as western science and mathematics and engineering was really worked out in the first few centuries of the common era by the persians and the arabs and the turks.
this includes the little system in arabic called al-jebra. and al-jebr roughly translates to “the system for reconciling disparate parts.“ al-jebr finally came into english as algebra. one example among many.
the arabic texts containing this mathematical wisdom finally made their way to europe -- which is to say spain -- in the 11th and 12th centuries. and when they arrived there was tremendous interest in translating this wisdom into a european language.
but there were problems. one problem is there are some sounds in arabic that just don't make it through a european voice box without lots of practice. trust me on that one. also, those very sounds tend not to be represented by the characters that are available in european languages.
here's one of the culprits. this is the letter sheen, and it makes the sound we think of as sh -- “sh.“ it's also the very first letter of the word shalan, which means “something“ just like the the english word “something“ -- some undefined, unknown thing.
now in arabic, we can make this definite by adding the definite article “al.“ so this is al-shalan -- the unknown thing. and this is a word that appears throughout early mathematics, such as this 10th century derivation of proofs.
the problem for the medieval spanish scholars who were tasked with translating this material is that the letter sheen and the word shalan can't be rendered into spanish because spanish doesn't have that sh, that “sh“ sound. so by convention, they created a rule in which they borrowed the ck sound, “ck“ sound, from the classical greek in the form of the letter kai.
later when this material was translated into a common european language, which is to say latin, they simply replaced the greek kai with the latin x. and once that happened, once this material was in latin, it formed the basis for mathematics textbooks for almost 600 years.
but now we have the answer to our question. why is it that x is the unknown? x is the unknown because you can't say “sh“ in spanish. (laughter) and i thought that was worth sharing.
Stress
Psychologist tell us that stress is a state of worry caused by the problem of living , such as too much work or study , heavy responsibilities , and quickened pace of life .
Statistics show that stress comes from every detail in our life . Financial problems , poor health , being laid off may be the stress that most adults now suffering . As students in the university , we are also under our special stress . While study , having to take various tests and submit a project against a deadline may put a great pressure on us . And the things make us felt stressed may be our parents's greater expectations on us than we could reach . Later , when we are likely to graduate , some other problems will also annoy us . I think we will worry a lot about our ability to compete in the job market and how we can best use what we've learned at college in our future job .
The chief problem we should face to is our atitude towards stress .People usually say they can not live in the sun except they escape from stress .
Ok , I think I was under large stress 3 minutes before , but now I am here and have finished my speech . Here is the last thing I want to add to my topic ,face to it and overcome it ,stress is also a piece of cake .
That is all . Thank you very much.