答案应该是： Had,not left
这是一个虚拟语气省略了if的倒装结构,原句是：If she hadn't left yesterday, she would meet the famous singer today.（如果她昨天没走,今天就能看到那个著名歌手了）
当虚拟语气的从句中有should,were,had（助动词）时,可省略if,用倒装,把它们放到主语的前面,但要注意如果从句是if的否定句,not不能和它们一起提前.