一、问题提出在我区的一次物理教研会上,有位教师向我提出这样一道选择题:如图所示一开口金属圆环,受热后开口将:()A、变大;B、不变;C、变小;D、不能确定.我看后认为答案为 A,即开口将变大,但该老师当即拿出一本书,其答案为 C,即开口将变小,同时还附有一段文字,说明开口将变小的理由,由此可见并非误排。 First, the problem was raised. At a physics teaching conference in our district, a teacher proposed to me such a multiple-choice question: As shown in the picture, an open metal ring is opened. After heating, the opening will be: () A, bigger; B, not Change; C, smaller; D, can not be determined. I think that the answer is A, that is, the opening will become larger, but the teacher immediately took out a book, the answer is C, that opening will be smaller, also attached There is a paragraph explaining the reason why the opening will be smaller. It can be seen that this is not a mis-arrangement.