Question

during the past 3 years=in the last 3 years（现在完成时） in the past、last 15 years

1.during the past 3 years=in the last 3 years（现在完成时）
2.in the past、last 15 years
我需要上面两个知识点的解析（区别）、例句，全面且简洁

Answer 1

意思其实差不多，就是所接时态不一样，during+时间段 多数跟过去时连用，in+时间段 则与完成时连用；这个知识点多数在单选出现，迷惑性挺高的。
例句：
1.During the past 3 years, the competition between the local and foreign banks spread in many field, and become more and more .
入世三年来，中外银行在各个领域展开了业务的竞争，而且这种竞争还有愈演愈烈之势。

2.Many new materials and technology have been designed in the last 15 years.
在过去的15年中有许多新型材料和技术问世。

In the past 15 years, innate immunity has come into its own.
过去15年来，先天性免疫逐渐受到重视。