材料：Navigation in the canal
It is not recommended that any person shall be allowed on the bridge or in the pilot house except the pilot and other representative of the Canal，and Master and such officers and other members of the crew of the vessel as may be necessary for its navigation and control，management，operation and safety．
Navigational aids are difficult to maintain and are reported to be unreliable in this waters．A considerable amount of shipping uses the canal and，in addition，many local fishing craft with nets may be encountered in the area.Since passage through the canal entails a run of more than 250 miles，long periods of considerable vigilance are necessary in order to maintain safe standards of navigation．
问题：PILOT HOUSE is referred to ______ in this passage．
A.the cabin in which the pilot stays
B.the space in which the rudder is located
C.the bridge of vessels
D.the cabin which is prepared for the pilot
SHIPPING is referred to ______ in this passage．A.he operations of transportation of goods by sea
B.the procedures of marine transportation business
C.the management of marine transportation business
D.the vessels and ships
The author implies that ______ ．A.even by making use of modern instrument it is difficult to maintain safety in this area
B.mariners should take it easy when navigating in this area
C.modern instrument should be used to control the safety of navigation in this area
D.it is dangerous when navigating in this area
The person on the bridge or in the pilot house shall be those ______ ．A.who are recommended
B.who are familiar with the navigation，management，operation and safety control
C.who are directly involved in the navigation，management，operation and safety control
D.who have nothing to do with the navigation，management，operation and safety control
请帮忙给出每个问题的正确答案和分析，谢谢！