很简单啊,就是过去时表示虚拟的,这个意思就是这件是过去的,它不可挽回,所以我虚拟而言之,当然了这只是个比方,是为了让你理解,if i were you,时间上不是过去,你要明白不是所有虚拟都是简单的像if i were you,而变换他们的时态会带来意思的变化,归根到底它是“语气”,if i had a sword,i would cut off his throat,（我没有）和if i have a sowrd,i will cut off his throat,（如果我有,我会这样做）两者都对,但意思不同,你明白了吗