50 The border between the two countries is a 3 km wide river which is _____ with hungry sharks.
(A)infested
(B)ingesting 
(C)digested 
(D)infringed 

46 Under Washington’s so-called “wet foot, dry foot policy,” Cuban migrants who make it onto U.S. soil are allowed to remain in the United States under a special immigration exception, while those _____ at sea are turned back. (A)interdict (B)intercept  (C)intercepted  (D)interested 

47 Which of the following are NOT man-made pollutants in the ocean？ (A)Pesticides (B)Marine  algae (C)Herbicides  (D)Detergents 

48 Which of the following words does NOT refer to a crime？ (A)Kidnapping (B)Counterfeiting  (C)Arson  (D)Snorkeling 

49 A woman acquires a phony passport. After she enters the country illegally, she is _____ by the Freedonia police and put into jail. (A)apprehended (B)comprehended  (C)complicated  (D)appreciated 

51 Which of the following is NOT a drug name？ (A)Heroin (B)Marijuana  (C)Cholesterol  (D)Cocaine 

52 In certain regions, ocean currents _____ trillions of decomposing plastic items and other trash into gigantic, swirling garbage patches. (A)oral (B)oval  (C)coral  (D)corral 

53 Several merchant ships are arriving at the scene of a distress incident. One of them must assume the duties of the Coordinator Surface Search（CSS）. Which of the following statements is TRUE？ (A)A tank vessel should never be assigned CSS duties unless only tank vessels are present. (B)CSS duties are always assumed by passenger vessels, dry cargo vessels, or tankers in that order of precedence. (C)The CSS must be established by a mutual agreement between the ships concerned. (D)The first vessel to arrive at the distress incident is designated as the CSS.

54 Messages from RCC：The helicopter will arrive in the position of the vessel in distress within one hour. (A)“ETA vessel in distress in one hour.” (B)“ETA distress position within one hour.” (C)“ETA distress position in one hour from now.” “ (D) ETA vessel in distress within one hour from now.”

55 A power-driven vessel which, because of her draught in relation on the available depth and width of navigable water, is severely restricted in her ability to deviate from the course she is following. This refers to _____. (A)a vessel unrestricted in her ability to manoeuvre (B)a vessel not under command (C)a vessel engaged in fishing (D)a vessel constrained by her draught

56 According to the passage, under a ban on Italian Parmesan cheese, a new source for fine Parmigiano-Reggiano is _____. (A)Belarus (B)Russia (C)Ukraine (D)France