塑性变形时，当主应力顺序σ1＞σ2＞σ3不变，且应变主轴方向不变时，则主应变的顺序为 发布时间：2017-11-09 12:59 │ 来源：www.tikuol.com 题型：填空题 问题： 塑性变形时，当主应力顺序σ1＞σ2＞σ3不变，且应变主轴方向不变时，则主应变的顺序为（）。
题型：填空题 阅读理解Dear Wei Lin: It was really good to hear from you again, but I was surprised to learn that you started smoking soonafter you went to the U.S. You said that smoking helps you relax. This might be true, but there are better ways to relax . And doctors tell us that smoking can only help us relax for a short time. I remember when you were in Taiwan, you were afraid that the air pollution might harm (对...有害处) your health. But don't you think you're also harming your health when you smoke? Smoking can hurt other people's health, too. And I've heard that some people have gotten cancer from second-hand smoke. So for your own health and for the health of others, please give up smoking … Yours, Alex 1. From the letter, we know that Wei Lin _______.[ ]A. couldn't smoke B. started smoking when he was old C. started smoking when he was in Taiwan D. learned to smoke after he went to U.S. 2. Why did he smoke?[ ]A. He was too busy. B. He enjoyed smoking. C. He needed it. D. He wanted to relax. 3. What does the writer think of smoking?[ ]A. He likes it very much. B. It is good to relax. C. It is harmful to health. D. It is OK to smoke a little. 4. Which of the following is NOT true according to the passage?[ ]A. Alex asked Wei Lin to give up smoking. B. Alex was Wei Lin's friend. C. Alex hated smoking because it hurt health. D. Wei Lin got cancer. 5. According to the writer, smoking is _______.[ ]A. harmful to smokers' health B. not good to others' health C. as harmful as air pollution D. All of the above 查看答案
题型：填空题 明末清初，在社会发展巨大变化的背景下，出现了一批反封建的民主思想家。明清时期产生反封建民主思想的主要原因是（）A.商品经济的迅速发展B.科学技术的不断进步C.封建制度的渐趋衰弱D.西方启蒙思想的影响 查看答案
