prep80 请教完成时态标识

ballparks

一般来讲我们说 during/within/in/since + the + past/last/recent + 时间短语为完成时态的标志，

举GWD 9－3 E项，和prep 16 C项解释

Because of wireless service costs plummeting  in the last year, and as mobile phones are increasingly common, many people now using their mobile phones to make calls across a wide region at night and on weekends, when numerous wireless companies provide unlimited airtime for a relatively small monthly fee.

1. Because of wireless service costs plummeting in the last year, and as mobile phones are increasingly common, many people
2. As the cost of wireless service plummeted in the last year and as mobile phones became increasingly common, many people
3. In the last year, with the cost of wireless service plummeting, and mobile phones have become increasingly common, there are many people
4. With the cost of wireless service plummeting in the last year and mobile phones becoming increasingly common, many people are
5. While the cost of wireless service has plummeted in the last year and mobile phones are increasingly common, many people are

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 [E]Correct. In the last year可以用完成式.

16. Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil, their descendents, popular known as killer bees had migrated as far north as Southern Texas.

A. Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil, 

B. In less than 35 years since releasing African honeybees outside Sao Paulo, Brazil,

C. In less than the 35 years since African honeybees had been released outside Sao Paulo, Brazil,

D. It took less than 35 years from the release of African honeybees outside Sao Paulo, Brazil, when

E. It took less than 35 years after the time that African honeybees were released outside Sao Paulo, Brazil, and then

C: in the 35 years 如果表示一段时间，应该加past, last等等；since替代了after改变句子原意，release这个动作没持续到migrated开始

请教prep 80， "during the last age" 显然为完成时态标志，为什么原句用了过去时呢，是因为逻辑意思需要？或者因为本来这种标识就不是非常严格，需要灵活使用？

80. Radiocarbon dating of fossils taken from caves on islands along southeastern Alaska’s coast suggest that at least a portion of the area was remaining ice-free during the last ice age.
A. suggest that at least a portion of the area was remaining
B. suggest at least a portion of the area remaining
C. suggests that at least a portion of the area remained
D. suggests at least a portion of the area that had remained
E. suggests at least a portion of the area to have remained （C）

ballparks

 好吧 谢了!!

XIAOHANMEIME

Q16 and 80's answers are C

Q16-African honeybees  parelle with the killer bee......

other answer choices are not matching the killer bee

Q80-during the ice age, the tense is past tense. u need to remember...

snowflowers

這個問題我也遇到 ，熟讀了百勇的文法書，與prep有很多出入，還是熟讀prep要的吧！

ballparks

我确实摘自白勇的GMAT语法全解，

刚刚又翻了一下书，是我断章取义了

找到书上一道题又补充了这样的解释：

“during two decades 不一定标志使用完成时态，是否使用完成时态由时间标志或者逻辑关系决定”

那么我又很想问， 是否意味着我们见到within/in/since + the + past/last/recent + 时间短语就可以确定为完成时态标志了呢？还是依然要具体问题具体分析？

IORIYAGAMI

一般来讲我们说 during/within/in/since + the + past/last/recent + 时间短语为完成时态的标志，

这是LZ总结的，还是摘自语法书的呢？during不是现在完成时的标志，语法书上把during列为过去时的标志，但事实上也有用现在完成时的情况，偶刚刚看了不少例子，有during时间状语的句子时态可由during后面的具体时间来区分：如果是during过去的一段时间（比如during those years, 1653-1888, the 1950s还有本题中的时间the last ice age），完成过去的时间，动作已经不再继续了，当然要用过去时态；如果是during一段时间，没有说明结束是在过去还是至今（比如during the past two month,），就用完成时。

一家之言。