問題在於你想用什麼時態 !

用現在時態, 必須 +es , 因前面 lesson 是第三者, 単數。

沒有三單的例子如下 :

1. lesson went on

2. lesson was gone on

3. lesson will go on

4. lesson is going

5. lesson is being gone on

6. lesson was being gone on

7. lesson will be going

8. lesson has gone on

9. lesson has been gone on

10.lesson had gone on

11.lesson had been gone on

12.lesson will have gone on

13.lesson will have been gone on

14.lesson has been going on

15.lesson had been going on

16.lesson will have been going on