题目

如图甲所示，是小明在水平桌面上探究“平面镜成像的特点”时的实验装置． （1）在实验中用平板玻璃代替平面镜，主要是利用玻璃透明的特点，便于 ；如果有3mm厚和2mm厚的两块玻璃板，应选择 mm厚的玻璃板做实验． （2）在竖立的玻璃板前A处放一支点燃的蜡烛，可以看到玻璃板后面出现蜡烛的像．小明拿另一支大小相同的蜡烛在玻璃板后面移动，当蜡烛移动到A′处时，可以看到它跟像完全重合．由此可以得出的结论是 ． （3）如果玻璃板放置选词填空。根据语境，用方框中所给词的适当形式填空。（每个词仅使用一次）owing to；in vain；in poor condition；from time to time；bring back to life；strike...into one’s hearts；bother；resist【1】Our teacher ________ the importance of safety ________________________，so we were all careful when crossing the streets.【2】The old house is ____________________. It needs to be repaired.【3】It is hard to ________ an invitation like that.【4】They decided to postpone the trip，______________ the change of the weather.【5】We still see her ________________________，but not very often.【6】Anyway, he was dead. No one could ________ him ____________________.【7】The girl tried ________________ to catch the butterfly on the flower.【8】—Thank you for the great favour you do me in face of difficulty.—It is no ________ at all. Helping others is also beneficial to me.