2015年6月英语六级冲刺试卷(二)

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#合辑# 机票是越早买越便宜吗？

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　　 选词填空 Section A

　　37、Questions37-46are based on the following passage.

　　It's a good idea to apply sunscreen before heading to the beach if you don't want to burn.But for marine animals like whales, they don't have that (36)___ Species like sperm whales can spend up to six hours at the ocean's surface in between dives, (37)___ in the sunlight.So how do they protect themselves from a serious case of sunburn? h turns out that their bodies have a similar defense (38)___against the sun's UV radiation as people.Blue whales--which have the lightest skin color of the three species--tan during their summer stay before (39) back to their northern feeding grounds: Sperm whales don't tan.They can receive an "overdose" of UV radiation during their hours at the ocean's surface, and they have proteins that (40)__ protect their cells from UV damage.This process is (41)___to how human bodies produce antioxidants in response to molecules that can cause a lot of genetic and cellular damage.And fin whales escape sun damage thanks to their high levels of melanin--a dark substance in the skin to protect humans from UV radiation.

　　Older whales and whales with less (42)___of melanin in their skin--like blue whales--had the greatest level of damage in their mtDNA.Fin whales, which had the greatest amount of melanin, had the least amount of mtDNA damage.

　　Now that the ozone layer that shields Earth from UV radiation is gradually (43)___ , it's important to know what the consequences are for whales and dolphins, especially for (44)___or endangered species.Although it's difficult to tell what causes many of these skin conditions, UV damage is one cause.Even though whales have (45)___ defenses toUV radiation, high exposure can still be harmful.

　　A.similar

　　B.diminishing

　　C.liability

　　D.migrating

　　E.mutual

　　F.mechanism

　　G.effectively

　　H.hazard

　　I.instantaneously

　　J.vulnerable

　　K.content

　　L.baking