(20 14? Jinan) Xiaoming used the device shown in the figure to conduct the experiment of "Exploring the imaging characteristics of flat mirror": (1) Xiaoming chose the glass plate instead of the glass plate. (1) replacing the flat mirror with a glass plate is mainly based on the transparency of the glass plate, which is convenient for determining the position of the image through the glass plate;

(2) Because the size of the object and the image are equal, the height and thickness of candles A and B must be exactly the same, otherwise the relationship between the object and the image cannot be compared;

(3) When looking for the position of the image of the candle nail, the eyes should observe on the side of the glass plate where the candle nail is placed;

(4) No matter how you move the candle in the back, it can't overlap with the image, that is, when the glass plate is not perpendicular to the horizontal desktop, the image is not perpendicular to the desktop, so it won't overlap;

(5) Because the image is formed by the reflection of light, and both sides of ordinary glass can reflect light to form two images, the student saw two images of the same candle through the glass plate. You can replace it with a thinner glass plate.

So the answer is: (1) it is convenient to determine the position of the image;

(2) The height and thickness are the same;

(3) a;

(4) The glass plate is not perpendicular to the desktop;

(5) both sides of the glass reflect at the same time, and each side forms an image; Replace the thinner glass plate.