familiar

adj.熟悉的;常见到的;常听说的;通晓;熟悉;随便的

n.常客;密友;高级官吏的家属;[天主]教皇[主教]的仆人

复数： familiars

He was humming a familiar tune.

他低声哼着一支熟悉的小曲。

He was back on familiar ground, dealing with the customers.

他又干起了与顾客打交道的老本行。

She looked around for a familiar face.

她环顾四周想寻找一个熟人。

Complaints about poor food in schools have become a familiar refrain.

抱怨学校饭菜差已是耳熟能详的老调了。