of构词，a

a piece of 一块（片）

a kind of 一种

a tuft of (hair，feathers，grass，etc.)

a skein of (yarn，thread，etc.)

a hank of (wool，silk，etc.)

a bob of (silk，hair，etc.)

a bowl of 一碗

a glass of

a cup of

a lot of

a type of

a number of