round pin

例句：

1. 1. She used a round pin to open the lock.
   她用一个圆头针打开了锁。
2. 2. The craftsman carefully placed the round pin into the hole.
   工匠小心翼翼地将圆头针放入孔中。
3. 3. The round pin was used to mark the center of the circle.
   圆头针被用来标记圆圈的中心。