以下哪句话的独立主格用的是对的?
1.Jack is running fast ,with his dog left behind.
2.Jack is running fast ,with his dog being left behind.
3.如果上面两句的with都省略还对吗?
请简要说明理由,
***注意：请先回答第1、2句哪句对或者都对，简要说明理由后再回答第3个问题。