However, this is often not the case

However, this is often not the case in practice, as many training images may only be annotated with a
partial set of labels, either due to the intensive effort to obtain the fully labeled training set or the
intrinsic ambiguities among the classes.

結果 (中文) 2:

然而，这往往是不实际的情况下，因为许多训练图像可以只用一个被注解
标签部分集，无论是由于密集的努力，以获得充分标记的训练集或
各个类中固有歧义。

結果 (中文) 3:

然而，这往往是在实践中的情况下，由于许多培训的图像可能只被注释与一个或部分的标签，无论是由于密集的努力，得到充分标记的训练集或本征的类之间的模糊性。