11.  When do we use the one and when do we use the orther ?

12.  Can you tell me which is correct and explain why.

13.  When do we use the one and when do we use the other?

14.  I forget all about my lessons and enjoy myself.

15.  Early in Monday, I leave for school and begin the hard work of a new week.

16.  Life of people can't be good and also can't be bad all the time.

17.  This story is frist and also is last.

18.  he take it to the town , and sell it.

19.  He is worker and works in a big factory called Xing Fei.

20.  You are shaking your thinner arms and shaking down the fruits on the trees.