n.伸展；扩大；延长部分；电话分机
名词extension的复数形式.
Your back exercises should include lat pull-downs and back extensions. 背部的练习应包括前曲和后背伸展。
These temporary hive extensions contain frames of empty comb for the bees to fill with honey. 这些临时的蜂箱扩大了能包含为蜜蜂准备的空巢结构去存蜜。
There are telephone extensions in every office. 每间办公室都有电话分机。
