阅读短文，选择合适的答案。

    I study at Yu Hong Primary School in Guangzhou. I have forty-seven classmates (同学). Twenty-three are boys and twenty-four are girls. Our classroom is a nice one. It's very big. There are four windows and two doors in it. We have a big blackboard and a small one. The big one is for our teachers and the small one is for us. Mr. Li is our Chinese teacher. He is an old man. We don't like him at all. But Miss Chen, our English teacher, is a young woman. She is very nice. We all like her very much. So we like English the best. We often play basketball with Miss Chen.

小明在做“探究平面镜成像”的实验时，将一块玻璃板竖直放在水平台上，再取两个完全相同的蜡烛A和B，点燃玻璃板前的蜡烛A，进行观察，如图所示，在此实验中：

（1）小明选择玻璃板代替镜子进行实验的目的是 ____　．

（2）为了更好完成实验，小明应在 ____（选填“较暗”或“较亮”）．

（3）小明将蜡烛逐渐远离玻璃板时，像的大小 ____（选填“变大”、“变小”或“不变”）．