PREP1-3

借个题目问since的用法。

Longman上说，Since
                        is
usually followed by a time expression ('last year', 'this morning', '4
o'clock' etc) or by the simple past tense. Use the present perfect or
the past perfect in the other clause。但是Prep note上说：Since是现在完成时的标志和had migrated矛盾。我记得新东方也说since是现在完成时的标志。那么，到底可不可以用过去完成时呢？按照longman的说法，看来是可以的样子。那么这个题目之所以不选BC并不是和后面的had migrated矛盾而是因为since的用法不对，后面应该跟一个time expression或者是过去时。这样解释对么？

Less than 35 years after the release
of African honeybees outside Sao Paulo, Brazil, their
descendants, popularly 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 the 35 years after the time
that African honeybees were released outside Sao Paulo, Brazil, and then

我觉得你提供的这个非常有帮助

多谢

我觉得你分析的很明白了

只是，since+past perfect在GMAT语法里面从来没有对过，所以见到就当它错