By the following semester, it is likely that the old professor () on the campus of California University for two decades.

A. will have to be teaching

B. will have been taught

C. will have been teaching

D. will be teaching

对于使用寿命接近或已经超过设计寿命的管道，检验时应进行（）检验，必要时应取样进行力学性能试验或化学成分分析。