: ( 432)
This move leaves too many White weaknesses in the centre, and does not even have a strong effect on Black's top left corner.
, :
Black answers White's invasion passively, and takes some of White's stones in the lower left corner, in exchange.
: (A 490)
White cannot capture Black's two stones, with .
(B 491)
If she does not play at now, or at some other point nearby, then Black plays at - this defends the two Black stones, and threatens to kill all the White stones on the left.