a skein of yarn的用法和样例：
- When they had paid, he had caught sight of a skein of vivid red yarn in the young man's canvas bag.
- Now that we have the Noni Bags available, we thought we would mention that many of the patterns require one skein of one colour, but with two strands of yarn held together.
- She passed me a skein of wool.
- Lately, there has been a skein of such dangerous discoveries, one with deadly consequences.