Array of arrays

Hi im trying to make a tetris game for better learning, and decided to place each piece on its own variable, what i would like to be able to do is make an array of arrays so i can sort out the lines to the pieces.

i know that to make an array of game objects its:

var line1: GameObject[];
var line2: GameObject[];
var line3: GameObject[];
var line4: GameObject[];
var line5: GameObject[];

but i would like to put these 5 gameobject arrays into a separate array, so i can like go up or down a line really easy. i hope this makes sense heh.

You can use a 2D array.

var lines : GameObject[,];

See here for an example of Tetris in Unity.