They are looking into (调查) the matter.

句子语法结构分析如下

主语：They（他们）

谓语：are looking into（正在调查）

宾语：the matter（这件事件）

请老师帮忙划一下句子成分，再请问介词into是后面the matter的引导词还是和前面的looking组成介词动词？感谢老师的回答。

解答如下:

look into 为动词+介词构成的一个短语动词(固定搭配），有自己确切意思“考察；调查；研究 ”

He had once looked into buying his own island off Nova Scotia.

他曾一度考察过在新斯科舍附近购买岛屿。

It should also look into the possibilities of wind-generated electricity. 

还会对风力发电的可能性进行研究。

They set up a working party to look into the issue.  

他们设立了一个特别工作组来调查这个问题。

The college principal promised to look into the matter.  

学院院长答应研究这个问题。

The government will look into how to reduce unemployment.  

政府将研究如何降低失业率.