knuckling

Charlotte rapped on the window with her knuckles.

夏洛特用指节轻敲着窗户。

He got a rap over the knuckles for spending too much money on his business lunches.

因为商上花钱太多，他挨了顿批评。

Our fingers bend at the knuckle.

我们的手指指节处弯曲。

The most common type of joint in the human body is the diarthrodial joint -- knuckles and shoulders are examples -- in which two bones come together in a capsule.

人体中最常见的节是运动节，如指节和肩节等，节处的个囊状物把两根骨头结合。