Common pd in signal language learning mainly showed in the following : ca n ' t understand the objects the mathematics signals represent ; scare of extensive cognition to the mathematics objects which mathematics signals represent . do n ' t understand the meaning expressed by signal language . the same signal forms can express different meanings , and different signal forms can express the same meaning , if student separate signal language from its maths meaning contained in it , the ml they mastered is a kind of signal game without any meaning ; not mastering various forms of signal language ( signal language has many equal forms ) or only mastering one kind or several kinds forms , the cognition to signals are not enough 符号语言学习的常见心理偏差主要表现存不能理解数学符号代表的对象，缺乏对数学符号所表示的数学对象的广泛性的认识；不明白符号语言表达的含义，如果将符号语言与所表达的数学含义相脱离，学生所掌握的数学语言就是毫无意义的符号游戏；掌握不了符号语言的各种变化形式，符号语言有许多的等价形式，如果只是掌握其中的一种或几种形式，对它的认识将不够充分。
3 in the years of cold spring , the inner mongolia high and the aliushen low are strengthened with the low index of the east asia trough and the negative anomaly center of temperature over northeast china from surface to tropopause while the contrary conditions occur in the years of warm spring 3 、东北地区出现春季低温的主要环流特征是：内蒙古高压，阿留申低压的强度加强；阿流申低压指数以及东亚大槽强度指数减弱，东北地区从地面到对流层顶处在温度负距平中心内，东北地区春季高温时则出现与上面相反的变化形式。
