各种生产类型的主要工艺特征是什么？
参考答案：
（1）单件生产的工艺特征是：毛坯精度低，加工余量大；采用通用机床、通用夹具、通用刀具及万能量具；对工人技术水平要求较高。
（2）成批生产的工艺特征是：毛坯精度及加工余量中等；采用通用机床及部分专用机床，一般采用专用夹具，部分采用划线方法保证尺寸精度，较多采用专用刀具及量具；要求工人具有一般技术水平。
（3）大批量生产的工艺特征是：毛坯精度高，加工余量小；广泛采用专用机床及自动机床、专用夹具、专用刀具、量具；对工人技术水平要求不高。
While learning the science lessons, I used to get a doubt--why ear, nose, tongue and eyes should be called as special senses? The basic reason is that these are the channels through which we maintain contact with the surroundings. Though apparently it may feel like these are individual sensory organs, they do show some connectivity. Interestingly, our hearing is less sharp after we eat a heavy food. Isn’t it good for a sound nap after a stomach-full meal? That does not mean we go deaf after a meal, but the hearing pitch（强度）does change after a heavy meal. We usually give credit of the taste to our tongue, but do you know that unless saliva（唾液）dissolves something, our tongue cannot recognize the taste of the food eaten. Taste is nothing but the food chemicals dissolved in the saliva being sensed by the taste buds（味蕾）present on the tongue. Try to dry off your tongue and mouth with a tissue paper and then taste something. Women are much better smellers than men. They are born with this characteristic ability and can correctly recognize the exact fragrance of the sample. We all can store almost 50,000 different smells, which are strongly tied to the memories. Pupils（瞳孔）do not respond to light alone, but to the slightest bit of noise around too. Thus surgeons, watchmakers and those professionals who have to perform a much delicate job do prefer to have a sound-free environment. Even a small noise can enlarge their pupils, change the focus and make their vision less clear. Each and every one of us has a particular or individualistic or characteristic smell, which is unique to us, except the twins. This smell is very subtle yet can be sensed even by a newborn. It may be due to this smell that the newborn recognizes the presence of his parents around. 小题1:What may happen after you have had a rich lunch?
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