在线学习的一大优点是它的灵活性。

The great ___virtue of online learning is its flexibility.

现代技术提供了许多优点，包括效率和便利性。

Modern technology offers numerous ___virtues, including efficiency and convenience.

这种方法的一个关键优点是它的成本效益。

One key ___virtue of this approach is its cost-effectiveness.