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现在完成时，during+时间，表示在某段时间里，常用作现在完成时态的时间状语。现在完成时态常接时间状语：如so far，by now，up to(till)now，for，since，in the past few…，during the last few…等。We have planted more than two thousand trees by now。
1. 表示“在……期间”，是介词，不要将其误用作连词。如：
他在巴黎期间，与他的朋友住在一起。
误：During he was in Paris, he lived with his friends.
正：While he was in Paris, he lived with his friends.
正：During his stay in Paris, he lived with his friends.
2. during 和 for 均可表示一段时间，但两者有差别。
(1) during 通常表示事件发生在何时(when)，而for则表示事件持续了多长时间(how long)。如：
He was in hospital for six weeks during the summer. 他在夏天住了 6 个星期的医院。
(2) 两者之后均可接由 the whole 引起的时间短语，但通常不能接由 all 引起的时间短语。如：
他整个夏天都住在那儿。
正：He stayed there for [during] the whole summer.
误：He stayed there for [during] all the summer.
(3) 在“数词+时间名词”之前以及在some time, a long time之类表示泛指一段时间的词组之前，可用介词 for，但不用 during。如：
He lived here for ten years (for some time). 他在这儿住过 10 年(一段时间)。
3. during与in均可表示“时间点”，有时可互换。如：
I'll be on holiday in [during] August. 我将在8月度假。
He woke up three times in [during] the night. 夜里他醒了 3 次。