______ provided the methodological foundation for materials for the teaching and its principles formed the basis of such widely used series as English 900 and Success With English.

A．The Direct Method

B．The Oral Approach

C．The Audiolingual Method

D．The Communicative Approach

IGBT属于（）器件。

A、电流控制型

B、电压控制型

C、功率控制器

D、电压控制功率