1.I am very tired so I can't concentrate properly

-] If.....

2.Fail to pay and they will cut off the electricity

-] If.....

3.She is very busy so she can't go out tonight

-] If.....

4.I don't know anything about her back ground , so I can't tell you 

-] If....

5.Don't touch that wire or you may get an electric shock

-] If...

6.If it doesn't rain soon , the crops will be lost

-] Unless.....

7. He doesn't give you good advice because he isn't your true friend

-] If.....

8.We come late because the rain is so heavy

-] If....

9.You don't get better marks because you don't study harder

-] If.....

10.She's so shy , that why she doesn't have many friend

-] If....

11.Alice may miss the train . But the can get the next one

-] If.....