select elements in a list

list = {{1, 11}, {2, 7}, {4, 2}, {7, 9}, {-2, 3}, {-1, 10}};

Select[list, #[[2]] > 8 &][[All, 1]]

{1, 7, -1}

OR using Pick

Pick[list[[All, 1]], UnitStep[list[[All, 2]] - 8], 1]

{1, 7, -1}

list = {{1, 11}, {2, 7}, {4, 2}, {7, 9}, {-2, 3}, {-1, 10}};
Cases[list, {a_, b_} /; b > 8 :> a]
(* {1, 7, -1} *)

What I'm doing above is to use Cases to select only those sublists whose second element is greater than 8,

Cases[list, {a_, b_} /; b > 8]
(* {{1, 11}, {7, 9}, {-1, 10}} *)

The /; notation defines a Condition. Then I'm applying a :> to make a replacement, in this case keeping only the first element, look at RuleDelayed

Pick[list[[All, 1]], # > 8 & /@ list[[All, 2]]]

or

Pick[#[[1]], # > 8 & /@ #[[2]]] &@Transpose[list]

{1, 7, -1}