Part 2 question on capturing in Go

[i280]

Second question for me

In Dia 2 I see Black has surrounded, why it is said white cannot be captured?

[Kosh]

To capture the White stones, Black would need to fill all five spots inside White’s territory.

Note firstly that the spot at the top (F9) is an illegal move for Black (as it stands). If Black starts with the other four spots, the last of those will also become an illegal move due to self-capture.

This is an example of having two eyes for life.

[i280]

Thanks…