The word “critical” in the sentence “This is a critical period as any loss of propulsion, or steering, can lead to collision, grounding, or other damage to the ship” can be best replaced by （）.

A.Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired on the spot
B.Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired on the next port of call
C.Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired until the next stop
D.Any leaks in piping, propeller shaft, machinery, tanks, will have to be at least patched up

A.In times of heavy weather, it is extremely dangerous if a seaman is not enough tall
B.In times of heavy weather, it is extremely dangerous if a crew is very short
C.In case of bad weather, it is particularly dangerous if there is a shortage in personnel
D.In case of bad weather, it is particularly dangerous if there are enough personnel

A.should not be carried out during the watches
B.can only be carried out in port
C.is a kind of maintenances carried out prior to the occurrence
D.is a kind of maintenances carried out after the occurrence