句型     one by one    一個 = one after another

1.   After assembly, students came into the classroom one by one.

= After assembly, students came into the classroom one after another.

2.   Monica does go well these days because good things have happened to her one after another and bad things have never happened. 

3.   Kate’s daughter ate too much chocolate candy.  She ate it one by one in dinner party.

4.   After ripping tickets, the audience waiting in line outside the front door get into the theater one after another.   

5.   The party is coming close to the end.  At the reception area, guests say goodbye to Mr. and Mrs. Simpson and leave one after another.

6.   After the workers of the movie theater ripped the tickets, the audience came in and took their seats one after another. 

      = After the workers of the movie theater ripped the tickets, the audience came in and took their seats one by one.

7.   Many bills will come in one after another at around the end of each month.

      (around是副詞)

      = Many bills will come in one after another around the end of each month.

      (around是介系詞) 

8.   He is a lucky man because happy things happened to him one after another.

9.   On one autumn evening, I saw a group of ducks walking across the street one after another.

10.    When the fruits like guavas, apples, peaches, and pears are ripe and no one wants to pluck them, they all will fall to the ground one by one.

         = When the fruits like guavas, apples, peaches, and pears are ripe and no one wants to pluck them, they will all fall to the ground one by one.

11.    Passengers stand in line and get on and off the bus one by one.  That is good manners that modern citizens should have.

來源：http://tw.myblog.yahoo.com/tw_english_study/article?mid=1264&prev=1274&l=f&fid=12