if you were narrating in the present tense, you'd say the following: 'as of today, the bees have migrated as far north as southern texas.' therefore, since this sentence describes a situation in the past (it describes the situation 35 years after the release, which is before the present), you translate all present-tense verbs into the past tense. this turns 'have migrated' into 'had migrated'.
there is no explicit description of the 'second event' you're looking for in this problem, which is what makes it difficult. instead, the 'second
event' is the point on the timeline, 35 years after the release of the bees. because the sentence describes a trend whose relevance continues up to and through that point, a perfect tense is appropriate.
wrong answers:
*
choice b implies that the honeybees' descendants somehow released them
(perhaps a very bizarre case of karmic cycles, but absurd no matter
what).
* choice c: 'the 35 years since' implies that the present
is 35 years after the release date. not only does this conflict with
the meaning of the original, but it also renders the past perfect (from
the underlined part) inappropriate: you'd need present perfect in this
case. also, since the release is a point event, it would belong in the
simple past.
* choice d: in this sentence, the commas +
non-essential modifier ('..., when') seem to imply that the
descendants' migration took place simultaneously with the release of
the original honeybees. in addition, in this sentence, 'it' refers to
some unspecified event (it can't refer to the descendants' migration,
for the aforementioned reasons).
* choice e: all kinds of problems with this one. if you don't see what's wrong with it, reply and we will elaborate.
首先题目中出现Cuban and the Jamaican 的原句：Moreover, the Puerto Rican twig species closely resembles the twig species of Cuba, Hispaniola, and Jamaica in morphology, habitat use, and behavior.
这里是说这些区域的twig species 有着相似的resembles in morphology, habitat use, and behavior.
问题是却是tree-d?
首先Cuban and the Jamaican 的原句的后一句：Likewise, the specialists for other habitats are similar across the islands. 证实其他的habitats 在不同区域都有相似性。
都有什么养的habitats？tree-d habitats 怎样？
原句：occupy different habitats: some live only in the grass, some only on tree trunks, and some only on twigs. These species also differ morpho-logically: grass dwellers are slender with long tails, tree-dwellers are stocky with long legs
来自RON
"evidence to suggest" and "evidence that suggests" are both acceptable in this sort of context. neither is a basis for elimination.
normally you would see "evidence that suggests..."
however, they've used "evidence to suggest..." here, in order to avoid writing evidence THAT suggests THAT xxxxx. not because it's wrong -- just because it's ugly.
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this is a tricky one.
if you were narrating in the present tense, you'd say the following: 'as of today, the bees have migrated as far north as southern texas.' therefore, since this sentence describes a situation in the past (it describes the situation 35 years after the release, which is before the present), you translate all present-tense verbs into the past tense. this turns 'have migrated' into 'had migrated'.
there is no explicit description of the 'second event' you're looking for in this problem, which is what makes it difficult. instead, the 'second
event' is the point on the timeline, 35 years after the release of the bees. because the sentence describes a trend whose relevance continues up to and through that point, a perfect tense is appropriate.
wrong answers:
*
choice b implies that the honeybees' descendants somehow released them
(perhaps a very bizarre case of karmic cycles, but absurd no matter
what).
* choice c: 'the 35 years since' implies that the present
is 35 years after the release date. not only does this conflict with
the meaning of the original, but it also renders the past perfect (from
the underlined part) inappropriate: you'd need present perfect in this
case. also, since the release is a point event, it would belong in the
simple past.
* choice d: in this sentence, the commas +
non-essential modifier ('..., when') seem to imply that the
descendants' migration took place simultaneously with the release of
the original honeybees. in addition, in this sentence, 'it' refers to
some unspecified event (it can't refer to the descendants' migration,
for the aforementioned reasons).
* choice e: all kinds of problems with this one. if you don't see what's wrong with it, reply and we will elaborate.