operational time的用法和样例：
例句
- Afterwards, the proliferation activity of fibroblast was decreased along with the time of culture and the increase of doses of fluoride.
随着氟质量浓度的增加和氟作用时间的延长，成纤维细胞的增殖活力明显减弱。 - The electromagnetic intensity, the acting time and the heat effect are the main factors which influence the separating result.
磁场强度及作用时间及磁场的热效应是影响分离效果的主要因素。
