Execution time average over all the data sets per unlabelled sample for the two first iteration of the AL process for each AL strategy with their standard deviation.

Execution time average over all the data sets per unlabelled sample for the two first iteration of the AL process for each AL strategy with their standard deviation.

针对每种主动学习（Active Learning）策略，在其主动学习流程的前两轮迭代中，每个未标注样本在全部数据集上的平均执行时长及其标准差。