11.Around the world coral reefs(珊瑚礁) are facing threats brought by climate change and great changes in sea temperatures.While ocean warming has been the primary focus for scientists and ocean policy managers,cold events can also whiten corals.A new study by scientists compared damage to corals caused by heat as well as cold stress.The results show that cool temperatures can cause more damage in the short term,but heat is more destructive in the long run.
Climate change is widely known to produce warming conditions in the oceans,but extreme cold-water events have become more frequent and serious as well.I 2010,for example,coral reefs around the world faced one of the coldest winters and one of the hottest summers on record.
During a unique experiment,corals under cold temperatures suffered greater damage in just days compared with the heat treated corals.Yet the researchers found that corals were eventually able to adjust to the cold conditions,make their health stable and continue to grow.However,over the long term corals subjected to heat suffered more greatly than those in cold,with evidence of severe whitening and growth stoppage,which leads to death.
The coral's ability to adjust to cool temperatures surprised the researchers,who say the study's results show the complexities of monitoring coral health in response to different environmental factors.
"Global warming is associated with increases but also decreases of temperatures,"said Deheyn,one of the researchers."Not much has been known about the comparative effects of temperature decrease on corals.These results are important because they show that corals react differently to temperature differences,which is important for future management of coral reefs in the field of climate change."
66.According to the first paragraph,we know thatB.
A.different corals suffer differently by climate change.
B.both heat and cold stress affect corals.
C.cool temperature is more destructive to corals.
D.it's hard to know the effect of climate change on corals.
67.The phrase"subjected to"(in Paragraph 3)is closest in meaning to"C
".
A.referred to
B.adjusted to
C.exposed to
D.stuck to
68.By"Not much has been known about…"Deheyn probably means thatA.
A.we know very little about the effects of temperature decrease on corals
B.temperature decrease is not expected to have a bad effect on corals
C.it makes no sense to study the effects of temperature decrease on corals
D.corals may not have been affected by the decrease in temperature.
69.What is the passage mainly about?D
A.measures should be taken to control global warming.
B.Climate change has resulted in more cold currents.
C.Heat is responsible for the destruction of corals.
D.Heat can cold damage corals in their own ways.