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题库 / Prep2007E2-SC-8
Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.
has long appeared that it was immune from
has long appeared to have been immune from
has long appeared as being immune to
had long appeared immune to
had long appeared that it was immune to
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明显d更简洁
e
where it had long appeared that it was immune to 啰嗦
第一个it是形式主语，是臭氧层对人类的影响免疫这件事显现了出来，不是臭氧层显现出来臭氧层对人类的影响免疫
too wordy. "appeared immune" is just fine on its own. Notice that we have "it appeared immune." The "it" here refers to the ozone. Thus, to say: "it appeared that it was immune" would be unnecessary.
it appeared后面加从句it blah blah是redundant，appear作为系动词，后面可以直接加形容词做表语。这样最为简洁
B tohavedone ，todo不定式的过去时，太冗长了，和前面的had appear重复，而且主要是前面的时态错
appear as thebeing 错
immute to... 不受...影响
immune from... 免除...
"immune from" means free of exempt from (eg. immune from prosecution), whereas "immune to" means not susceptible (eg. immune to chicken pox).
B中appear to后的have been immune from的have been与前面的has long重复
C没有appear as being这种用法
Dhad done很好的表现了分号前后句子的时间关系 。
immune from... 免除...
1. 时态上，AE都有错，主句has／had appeared，后面从句was，就是错误的。这里从句应该与主语时态是一致的。
2 在we have now realized已经是现在完成，意味着在过去某个时间点之前我们都以为ozone是 immune from human influence，自然应该用过去完成时态。
3. it appeared后面加从句it blah blah是redundant，appear作为系动词，后面可以直接加形容词做表语。这样最为简洁清楚。
Excellent
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