What node is return by before$($B$)?$ In other words, what is the predecessor of

$B?$

What node is return by before$($Q$)?$ In other words, what is the predecessor

of $Q?$

What node is return by before$($L$)?$ In other words, what is the predecessor of

L$?$

What node is return by before$($G$)?$ In other words, what is the predecessor

of $G?$

What node is return by before$($O$)?$ In other words, what is the predecessor

of $O?$