不少教师意识到，质疑问难能发展学生思维，体现学生的主体作用，但是在教学实践中往往顾虑太多，放不开手脚。其一，怕学生的提问打乱了讲课程序；其二，怕学生追根问底，教师回答不出而难堪；其三，怕学生漫天提问，达不到教学目的；其四，怕耽误教学时间，完不成教学任... Many teachers have realized that it is difficult to develop students' thinking in questioning and embody the main role of students. However, in teaching practice, they often think too much and can not let themselves go. First, fear of students' questions upset the lecture process; Second, fear of students to pursue roots, the teacher can not answer and embarrassed; Third, afraid of students asking questions, not up to teaching purposes; Fourth, fear of delays in teaching time , Can not finish teaching any ...