焊后进行正火处理是为了改善焊接接头的力学性能，细化晶粒。
参考答案：对
The most common symptom associated with bladder cancer is
A. burning on urination.B. frequent infections.C. painless hematuria.D. decreasing urine output.
京剧界以前曾有八位艺术家被誉为“八骏马”，指的是哪八位表演艺术家？
