说出分离缸液面控制指标（）

A、1/3-2/3液面计

B、1/2-2/3液面计

C、1/8-2/8液面计

A certain clock marks every hour by striking a number of times equal to the hour and the time required for a stroke is exactly equal to the time interval between strokes. At 6:00 the time lapse between the beginning of the first stroke and the end of the last stroke is 22 seconds. At 12:00, how many seconds elapse between the beginning of the first stroke and the end of the last stroke ？（）

A．72

B．50

C．48

D．46

E．44