How can I find out if the mirror is real?

Don't differ too much in length and width (except for famous brand mirrors, because the general mirrors are different in length and width and uneven in texture, resulting in inconsistent imaging).

2.

Be sure to be big enough. The general standard is that when the distance is 50 cm, you can see your hand when you put your hand on your ear, and your finger is up)

3.

The shape is square, not round, just like 1.

4.

Shine in the sun, because the mirror image is suitable for light, so shine in the sun, the most real.