题型:问答题 简答题 The shy girl felt _____ and uncomfortable when she could not answer her teacher’s questions. [ ]A. amazed B. embarrassed C. curious D. amused 查看答案
题型:问答题 简答题 直探头探测厚250mm及500mm两锻件,若后者与前者耦合差4dB,材质衰减均为0.004dB/mm,前者底面回波为满幅度80%时,则后者底面回波应为其()。A、5%B、10%C、20%D、40% 查看答案