The reason ________ he explained was________ he was ill and unable to go to school.

A．why; that

B．why; because

C．which; because

D．which; that

霍尔效应式无触点点火系主要由内装霍尔传感器的（）、点火控制器、点火线圈等组成。

A.分电器

B.火花塞

C.配电器

D.附加电阻