请教一道PREP SC 十万火急！ 谢谢啦

crystal323

原句是Less than 35 years after the release of African honeybees outside SP,Brazil, their descendants, popularly known as killerbees, had migrated as far north as southern Texas.答案是原句对，但是我怎么都觉得前半句少介词呢, 但到前半句不是时间状语？请各位大侠解答一下~ 马上就要考试了。。。急啊