look back 是不及物动词词组么?那下面这个句子中的用法如何解释?

Question

既然look back 是不及物动词词组,那么The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past.中的look back用法如何解释?

Answer 1

look back 是一个不及物词组，这是对的。因此要加一个介词才能接宾语，所以they have been looking back into the past.　这里 only a relatively short time 作句子的状语，状语位置前置是为强调在一个相对短的时间里。