We for Jack at ten last Monday. He often kept us .
A:were waiting; waiting
B:were waiting; wait
C:waited; waiting
函数f(x)=( 12 )x+1,x∈﹣1,1的值域是____.
如图是“某城市不同时期人口密度与距市中心距离关系图”,读图回答下题.