1. He extended his hand, smiling brightly. (O)
2. Having lost my wallet before, I have no money. (O)
3. He sat in the chair with his legs crossing. (X)

이 중 3번만 틀리고 나머진 다 맞는데, 전 3문장 다 이해가 안됩니다.
알려주시면 감사하겠습니다~~