Mr. Wang, who is said to have immigrated to the USA, __ at No.2 Middle School in our city for twenty years.

A．has been teaching

B．was teaching

C．taught

D．has taught

教室里的日光灯是串联的还是并联的？某班的教室里共有8盏40W的日光灯，40W的日光灯工作时的电流为180mA，则8盏日光灯全部工作时，通过的总电流为多少A？