超导现象是指材料在一定条件下内部电阻变为零。这一特性却并未得到实际应用，其原因在于( )。

A．超导材料比较稀缺，不易普及

B．超导材料过于昂贵，普通人买不起

C．超导并不能节省多少能源

D．超导目前还不能在常温下实现

1) ______ the Oral Approach
2) ______ the Cognitive Approach
3) ______ the Communicative Approach
4) ______ the Audiolingnal Method
5) ______ the Direct Method
a) The use of drills and pattern practice is one of its distinctive features.
b) The practice techniques adopted in this approach generally consists of guided repetition and substitution activity.
c) Written work should be graded.
d) Role play and simulation activities are often thought to be one of the most effective ways of integrating language skills in the language classroom.
e) It seeks the intellectual understanding by the learner of the language as a system.