出口收费员按“现金收讫”键后票据打印机打印发票，栏杆抬起，此时若发现票据打印不清，收费员按（）键选择“重新打印发票”。

A. must utilize magnetic courses
B. must take set and drift into account
C. should be replotted hourly
D. should be started each time the vessel's position is fixed

A. 枕木烘炉法
B. 煤气烘炉法
C. 焦炭烘炉法