1, I don't buy it because I don't have enough mony
--> If I
2,I am busy now, so I can't help you
--> If
3, There will be a shortage of water unless it rains
--> If
4, John is fat because she eat many chips
--> If she
5, I'll only help you if you promise to try harder
--> Unless
6, If I doesn't rain soon , the crops will be lost
--> Unless
7, I am very tired so I can't concertrate properly
--> If
8, We don't have a garden, so we don't grow our own vegetables
--> If
9,He doesn't give you good advice because he isn't your true friend
--> If
10, We come late because the rain is so heavy
--> If
11, You don't get better marks because you don't study harder
--> If
12, She is very busy so she can't go out tonight
--> If
13, I don't know anything about her background, so I can't tell you
--> If
14, I wasn't hungry so I didn't feel like eating
--> If
15, She's so shy, that why she doesn't have many friends
--> If
16, I remembered Susan's birthday only because you reminded me about it
--> If
17, The car in front stopped so suddenly, so I crashed into its back
--> If
18, They painted the wall brown, that's why the house looked very dark
--> If
19, My brother will have enough money. He will buy a bicycle
--> If
20, I'll buy a new hat. I'll give it to you
--> If
21, You'll ask the teacher. He'll explain the lesson to you
--> If
22, I don't have enough money. I can't go on a long holiday this year
--> If
23, I don't haave a typewriter. I can't type it myself
--> If
24, I don't live in a big city, so I can't go to the cinema very often
--> If
25, Lan doesn't have a bike, she walk to school
--> If
26, He didn't hungry, so he missed the rain
--> If
27, We canceled our picnic because it rained very hard yesterday
--> If