often是频率副词,和sometimes,always,never,frequently等一样表示习惯性。
后接动词原形用于一般现在时；后接动词过去式用于一般过去时。
I often go running before work.
我常常在上班前跑步。
We often slept under the stars.
我们经常在夜空下露宿。
That doesn\'t happen very often.
那不常发生。
水利万物而不争,
而万物莫能与之争。
