新概念英语2册35课有一句话是：He became a bus driver and he has not regretted it.
我有俩个问题：
1.and连接的前后应该时态已知,and前面became是过去式,后面应该用had啊!
2.能否改成：He became a bus driver and he did not regret it.在句意和语法上有什么区别,可否互换.