11- The weather is bad , so we can not go picic.
If ___________________________________________________________
12- She fails the exam because She doesn’t study hard.
If ____________________________________________________________
13- I am tired, so I go to bed early 
If____________________________________________________________
14- I don’t have time, so I can not complete this exercise.
If ____________________________________________________________
15- they don’t play in our football team because They are older
If They ______________________________________________________
16- Mai is not my friend, so I don’t invite her to my birthday party.
If __________________________________________________________
17- I don’t tell my mother the truth. She is very bored now. 
If ________________________________________________________
18- Minh doesn’t do any exercise, so He is fat.
If _________________________________________________________
19- We are poor, so We can’t give him money
If we _______________________________________________________
20- I am fat because I eat too much fast food.
→ If I ______________________________________________