Left-handed people generally right brain is quite developed, so left-handed people logical reasoning ability slightly better, so people all say left-handed wise is reasonable. Of course, left-handed and disadvantages. According to foreign, according to a survey in early history, left-handed and right-handed people quite, but because the left-handed people to poison and bad natural environment is very sensitive, so when meet toxic substances and compare severe natural changes, such as: poisonous food, the nature of radiation, severe temperature change and other bad situation, left-handed people hurts than right-handed, so the number of left-handed than right-handed people less, along with the progress of the human way of life and the improvement of comfort, especially the European and American countries in these respects progress is quite large, so now the European and American countries the number of left-handed are on the rise of the state. In addition, left-handed people because brain developed therefore creates language competence than right-handed difference. So the advantage of left and right hands is relative, and do the best lay about. Left-handedness is write or use chopsticks natural handedness is left hand, also called the left. Research shows that, the left is about one over ten of the total population. Left-handedness is a kind of peculiar physiological phenomenon, left-handed is a unique group, left-handed that they face a special problem, also they have special advantages. Strictly left-handed is very rare. First of all, the movement of your hands including pull, cast, twist, hold, hold pen, needle, etc many action. There are quite a few people, different action handedness is different. If some people throw with right hand, left hand and get; Write most people are right-handed, but the microphone left-handed people and many. There are some action should be coordinated with both hands, such as plane picks, hoeing, a spade, swing, etc. Single hand action conventional one side of the hand, both hands is the dominant hand movements may be on the other side of the hand. Influence the determination of the left-handed another factor is correct the day after tomorrow. Almost every nation and different age, have the habit of correct left-handed. In the east, the main hand two action - use chopsticks and write, for is born left-handed people, more than the former in childhood has set up a file in the home were forcibly plate to come over, while the latter are often in the school was forced correct. But no matter how correct, these people are naturally handedness is still left. If considering the action of ability to walk, the problem is more complicated. The high jump, long jump, pedal, step, ceng and so on movement, many hand right-handed and action but with the left side is dominant. Perhaps, most people actually are double handed, always have a action body conventional side and other action of conventional side different. We look at yourself, or slightly carefully look at the people around you, you can find it. In order to have a standard, can generally think so: left-handed is write or use chopsticks natural handedness is left.According to this standard, the two action born left-handed and acquired were forcibly correction, is still regarded as left-handed; Some other action left-handed is not as left-handed. Natural this is only a say, people may set many different left-handed standard.
翻译：左撇子人一般右脑比较发达，所以左撇子人的逻辑推理能力略胜一筹，所以人们都说左撇子聪明是有道理的。
当然，左撇子也有缺点。根据外国的一份调查显示，在历史初期，左撇子和右撇子的人数是相当的，但是由于左撇子人对毒性与恶劣的自然环境比较敏感，所以当遇到有毒物质和比较剧烈的自然变化，比如：有毒性的食物、自然界的辐射、剧烈的气温变化等恶劣情况时，左撇子人受到的伤害比右撇子大，所以左撇子的数量要比右撇子人少，随着人类生活方式的进步以及舒适度的提高，尤其是欧美国家在这些方面进步相当大，所以现在欧美国家的左撇子人数是处于上升状态的。
另外，左撇子人因为右脑发达所以造成语言表达能力要比右撇子差。
所以左右手的优势都是相对而言的，做到左右开弓最好。左撇子是写字或用筷子的天生惯用手是左手的人，也叫左利。研究表明，左利者占总人口的十分之一左右。左撇子是一种奇特的生理现象，左撇子是一个独特的群体，惯用左手使他们面临特别的问题，也使他们具有特殊的优势。
严格意义上的左撇子是很罕见的。首先，手的动作包括拉、抛、拧、握、持笔、用针等许许多多动作。有相当一些人，不同的动作惯用手是不一样的。如有的人扔用右手，而接用左手；写字大部分人惯用右手，但持话筒惯用左手的人并不少。还有一些动作需双手协同，如刨镐、锄地、持锹、挥杆等。单手动作惯用某一侧手的人，双手动作的主导手有可能是另一侧的手。
影响左撇子判定的另一个因素是后天纠正。几乎各个民族和不同时代，都有纠正左撇子的习惯。在东方，手的最主要两项动作——用筷子和写字，对于正天生惯用左手的人，前者多在儿时已在家中被强行板过来，而后者又往往在学校被强行纠正。不过不管如何纠正，这些人天生惯用手仍是左手。如果考虑腿脚的动作，问题就更复杂了。跳高、跳远、蹬、踏、蹭等等动作，许多用手百分百的右撇子，腿脚的动作却以左侧为主导。
也许，大多数人其实都是双撇子，总有某项动作肢体的惯用侧与其它动作的惯用侧不同。我们审视一下自己，或略微仔细观察一下你身边的人，就可以发现这一点。
为了有一个标准，一般可以这样认为：左撇子是写字或用筷子的天生惯用手是左手的人。
依据这个标准，这两项动作天生惯用左手而后天被强行纠正的人，仍视为左撇子；其它一些动作惯用左手则不视为左撇子。自然这只是一家之说，人们可能定出许多不同的左撇子标准。
追问我要作为演讲，要个简短的，一两分钟的
追答不会吧！你在题目上又不写好.................对不起
你选一段吧！
看在我努力写的分上，给满分罗！谢谢！！！