in turn

by turns, in turn

这两个词组都与turn有关。
by turns: 意思是“轮流地”、“交替地”、“忽而...忽而...”（ one after another； alternately or in rotation）

• we read the poem by turns.
  我们轮流读这首诗。
• they sang songs by turns.
  他们轮流唱歌。
• he grew pale and red by turns.
  他的脸一会儿红一会儿白。

in turn: 意思是“依次相继地”（each in due succession）

• we sang the song in turn.
  我们依照次序唱歌。
• we were summoned in turn to see the judge.
  法官依次召见我们。

副词 in turn:

1. in proper order or sequence
   同义词：successively

1. The girls called out their names in turn.
   那些女孩儿逐一报出自己的名字。
2. Dilettante: a philanderer who seduces the several arts and letters each in turn for another.
   业余艺术爱好者——是轮流引诱文学与艺术的不专一者。
3. Move the camera to each of these position in turn, press save on the remote, then a number from1 to4.
   依次把摄像机移至各个位置，按遥控器上的Save键，然后按数字1－4。
4. She asked the same question of everyone in turn.
   她依次向每一个人问同样的问题。
5. The students clean the classroom everyday in turn.
   学生们每天轮流打扫教室。