一一 + 动词
one by one; each in turn, none left out
Structure
（把／对 一组事物） 一一 动词（拆下来、列举、回答、核对）
What it means
One by one: an action is applied to every member of a group in turn, with none left out.
How it is built
Group (as subject, after 把 or after 对) + 一一 + verb: 发言人对提问一一作了回答 (the spokesperson answered the questions one by one); 把零件一一拆下来.
When to use it
Written and formal: reports, notices, news, museum and archive work. Set phrases: 一一列举, 一一对应, 一一道来. In speech say 一个一个地 or 挨个儿.
Watch out
It needs a group: ✗ 把这个零件一一拆下来. 先后 and 陆续 say things happen one after another over time (客人陆续到了), not that one agent works through a set.
Examples
先把几百甚至上千个零件一一拆下来，拍照记录。
First its hundreds, even thousands, of parts come off one by one and are photographed and recorded.
记者会上，发言人对大家的提问一一作了回答。
At the press conference the spokesperson answered everyone’s questions one by one.
文物入库以前，工作人员要对照清单一一核对。
Before the objects go into storage, the staff check every one of them against the list.
Learn this in Lesson 235 · HSK 9+: 我在故宫修文物 (Restoring the Forbidden City’s treasures)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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