很多学生都有这样的考试经历：自认为会做的题，也做了若干步且计算无误，却意外地思路受阻，做不下去了．等考完后老师一评讲，才发现自己实在不该做不下去，从而使考试留下一些遗憾．其实，学生在解题过程中的思路受阻往往并没有被真的“堵死”，只要善于并及时地找到延续解题 Many students have such an examination experience: Since they thought they would do, they also made a number of steps and calculated correctly, but they unexpectedly blocked their thinking and could not go on. After the teacher finished the assessment, he discovered that he really could not do it, leaving the examination with some regret. In fact, the students’ thinking in the process of solving the problem is often not blocked, but as long as they are good and timely find the continuation problem.