[求助]Gmat Prep Honeybee

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

这道题考动词时态和指代

B：since releasing的逻辑主语是  descendents，错！

C：第一个had been用得不对，因为没有过去时间点做参照。应该用一般过去时。即使改成过去时也不对，因为in+ 时间段，主句还是应该用一般过去时。 C错

D/E it 指代不明，因为没有referent，也不是形式主语

A对，因为主句中的had been的时间参照点是 less than 35 years after the release. 从这句话可以看出，从release到现在至少有35yrs, 前面加了less 就说明是在现在的时间点以前的某个时间点，所以past perfect tense用得对