a lock of hair的用法和样例：
- A lock of hair had fallen down over her eyes.
- He kept a lock of her hair as a memento.
- A lock of hair tangled as if by elves.Often used in the plural.
- A lock of hair tangled as if by elves. Often used in the plural.
- A lock of dark hair curled across his forehead.
- He keeps a lock of her hair as a memento.