I have a string as given below: 

```
$str = "In order to successfully build your backlinks in a highly competitive industry (or if you're targeting highly competitive keywords), you have to get smart about your strategy. That means using the best back-link building tools available";

```

Now I want to split the string after every third word. That is I want..

```
split1 = in order to
split2 = successfully build your
split4 = backlinks in a

```

and so on till the end of the string. 

I have already done it using preg\_match\_all but it isn't giving me what I want. So can someone help me out with it to split the string using the split() or preg\_split or the explode() function. 

Thank you