汽轮机启动时,金属中的热应力大小是由其内外壁温差决定的,而上下汽缸温差是监视汽缸产生热弯曲的控制指标。
参考答案:对
Part A You will hear a lecture about shingles, an infectious disease. As you listen, answer Questions 1 to 10 by circling TRUE or FALSE. You will hear the talk ONLY ONCE. You now have 1 minute to read Question 1 to 10.Questions 1 to 10:
You are under a risk of developing shingles if you are vulnerable in the immune system.
从6台原装计算机和5台组装计算机中任意选取4台,其中原装与组装各2台的概率是__________。