for、since、during 都与时间段有关，常与时态结合考查。
要点讲解
- for + 时间段（与现在完成时/过去时连用）：for two years 两年了。
- since + 时间点/从句（与现在完成时连用）：since 2020 自从2020年，since he came here 自从他来到这里。
- for 回答 How long（多久）：—How long have you lived here? —For five years.
- during + 时间段/名词：during the holiday 在假期期间，during the meeting 在会议期间。
- since 与 for 转换：since 2020 = for about six years（时间点变时间段）。
经典例句
- She has worked here for ten years.
她在这里工作十年了。 - I have known him since 2018.
我从2018年就认识他了。 - We visited many places during the summer holiday.
暑假期间我们参观了许多地方。
易错提醒
- since 后接时间点（过去某个时刻），for 后接时间段；二者都是现在完成时的标志词。