_____ weekdays, he often gets up _____ six o'clock. [ ]

A. On, at

B. At, on

C. On, in

D. At, at

汽车暖风装置由（）等种类。

A、水暖式

B、风暖式

C、废气式

D、气暖式

E、电磁式

F、燃烧式