often是什么词性

副词 adv.
1.常常; 经常; 时常
I often go swimming in summer.
夏天我经常去游泳.
Often had I intended to speak of it.
我常想说说这件事.
How often does this magazine come out?
这本杂志多长时间出一期?
2.在大多数情况下
It's often difficult to translate poems.
翻译诗歌在许多情况下都是困难的.