"If I hadn't pratised when I was younger,” the musician says

"If I hadn't pratised when I was younger,” the musician says,"I____able to play so well now."
为什么答案是" wouldn't be "而不是" wouldn't have done
这是因为：从句和主句的时间不一样,从句是与过去的事实相反,用过去完成时,而主句的时间是now,现在,所以应该与现在的事实相反,用与现在事实相反的wouldn't be .