分析句子语法成分It might have been,but it didn’t have to be going th

it 主语
might 情态动词
have been going 谓语
but 连词 连接It might have been和it didn’t have to be
that fast 状语修饰going
为了好理解 你可以看成这样
It might have been going that fast,but it didn’t have to be going that fast.它或许是有那么快,但其实它没必要那么快
in order to appear to be separated from the sound.目的状语