2010年7月31日 星期六

SC_PP2-Q27


文章日期:2010-07-31 12:35
Ozone 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.

A) has long appeared that it was immune from

B) has long appeared to have been immune from

C) has long appeared as being immune to

D) had long appeared immune to

E) had long appeared that it was immune to
Tough call! Grammatically, there's nothing (much) wrong with E. The general preference when you're saying something "appeared" in some way is to just say it - don't need all those extra words. She had long appeared happy when visiting home for the holidays, but this year she was just plain grumpy. :)



Sort of a cross between idiomatic usage (appeared X) and concision (just say it without all the extra words!). So D is right.

[editor: the repetition of "it" in choice (e) is also highly undesirable. technically, this is not 100% wrong; the first "it" is of a special kind that doesn't require an antecedent. however, that construction is usually used only when there is NOT another "it" in the sentence to muddle things up. --ron]

mithra wrote:
I still don't get the usuage of "HAD" over "HAS", since it says "we have now realized" - That is present, so why can't we say "has appeared" (which means continue till present and now we realized it wasn't the case), whereas "had" would mean it appeared in PAST's PAST....I always get confused in this usage...help?
Thanks.


yeah, i can see how this is tough.

when you say "we have realized", though, this actually means that the realization took place in the PAST. (probably the recent past, but in the past nonetheless.)

here's the fuller deal with the present perfect ("has/have VERBed"):
if you use the present perfect with a POINT EVENT - i.e., an event that OCCURS AT A SINGLE INSTANCE IN TIME (realized, graduated, paid, given birth, scored, etc.) - then the event must have taken place IN THE PAST.
normally this is the quite recent past, but that's not always the case.
think about these:
my brother has obtained three business degrees.
the team has scored 32 points in this quarter.
Russia and the U.S. have sent expeditions to the moon.

these are all point events, and they are all PAST events.
the second is obviously in the very recent past, but the third is an event that happened over forty years ago (but to which we can still refer in the present perfect if it's relevant to the current topic of discussion). the first could be anywhere from a few minutes ago to 60-70 years ago, depending on my brother's age.

notice that, since these are "point" events, it's actually IMPOSSIBLE to refer to them in the present - unless you're narrating them, in the style of a sports announcer ("Demps scores a touchdown!")
so if you see them in the present perfect, they've already happened.

--

verb tenses are easily the toughest aspect of learning any language. hang in there.

"as being" isn't idiomatic -- i think that's really the only thing that's wrong with it.
in general, you should be suspicious of the word "being" unless it's used in a passive-voice construction, in which it could quite reasonably be correct.
i've never seen the word "being" in a correct construction that was not in the passive voice, although i cannot guarantee you that this couldn't happen.

nothing in the second sentence is going to influence the first sentence, since the first sentence is perfectly capable of standing on its own.
note, though, that it doesn't make any sense to switch tenses within the construction "has long appeared ... immune", since there is no actual change in time frames in that statement. (by contrast, notice that it makes sense to change tenses between "reaches" and "has/had appeared", since the former describes the current state of affairs while the latter describes a belief that persisted until a certain discovery was made. also note that "had appeared" makes more sense than "has appeared", since the moment at which this statement ceased to be true is in the past, not the present.)

in order not to have such a tense switch, we need one of the following two constructions:
"had long appeared immune"
or
"had long appeared to be immune"

the former is what is actually there, but the latter would be just as good.