one line in a variable is good but how assign in a variable multiple lines in text file?

--sample text file---- 

```
jeff              ->line0
35                ->line1
123456            ->line2
"this is          ->line3
the message       ->line4
from you"         ->line5

```

How to assign the line 3,4 and 5 to a single variable?

code:

```
<?php

    $lines = file('sample.txt');
    $vara= $lines[0];
    $varb= $lines[1];
    $varc= $lines[2];

   ?>

```