题目

________ she couldn't understand was ________ fewer and fewer students showed interest in her lessons. A . What；why B . That；what C . What；because D . Why；that 答案：A12．（1）图1是一个五角星ABCDE，你能计算出∠A+∠B+∠C+∠D+∠E的大小吗？（2）图2、3、4的变式图形中，上面的结论（图2中为∠A+∠EBD+∠C+∠D+∠E）成立吗？为什么？