一双，一串，一杯……这些英语词组是什么？

a pair of
trail string
a cup of
a bar of
a bottle of

一双a pair of
一串a series of（表一连串的事情）a string of(表物）
一杯a cup of
一对，一双，几些a couple of
一瓶a bottle of
一（玻璃）杯a glass of
一片a piece of
一套/组/副a set of
一袋a bag of
一碗a bowl of
一公斤a kilo of
一种a kind of

a pair of
a cup of
a bar of
a bottle of

a pair of
a cup of
a bar of
a bottle of