Training a dog requires the expenditure of time and effort. 训练一条狗需化时间和精力。
This technology is very useful for decreasing the time of hydrogenation catalyst presulfurization and the equipment eroding as well as pollution. 该工艺对缩短加氢催化剂的预硫化时间,减少调备腐蚀和环境污染,具有非常积极的意义。