影响电火花加工精度的主要因素是什么？
参考答案：
影响电火花加工精度的主要因素：
（4）脉冲电源的质量和加工参数的选择——包括脉冲宽度ti，放电
时间te，放电周期tp，放电重复频率f，峰值电流ie等。
（5）工作液——工作液可以提高放电点的能量密度，增大放电时的
爆炸力，使熔化的金属容易排出。
（6）电极材料及电极设计
（7）工艺系统的制造及安装高速的精度和质量。
阅读下列短文，根据短文内容完成表格中所缺信息，每空一词. “USA? Britain? Which country is better to study in?” We often hear such discussions. As China open its door, it is a dream for many Chinese students to study abroad. They want to learn about the outside world. It’s true that studying abroad can help students develop themselves. Their foreign language skills will be improved and it may be easier to find jobs. But there are problems that should be considered. Language is the first. Students must spend a lot of time learning another language. Students must also learn to live without parents’ care and deal with all kinds of things they haven’t to do before, like looking after themselves. There are reports about Chineses students abroad running into an ocean of difficulties and giving up finally. When they have to take care of themselves, it is hard for students to study well. Finally, studying abroad brings a heavy burden to the family. For most Chinese parents, the cost of studying abroad is very high. But is it worth it? We know that there are many famous people who have achieved success through their hard work in China. Liu Xiang is a good example. Once an American teacher invited him there, but he refused. He kept training hard with his Chinese teacher. He surprised the world when he won a gold medal at the Athens Olympic Games. So when you winder which country is better to study in, think it again.
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