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In 1999, on Halloween, I and my friends decided to go to an abandoned house at the end of the street. The owner of the house had died long ago, so the house was ramshackle. We had been planning to go there when we were kids but we were afraid. It was fascinating for us to visit it because it had been said that there was a ghost. At 3 a.m, when everybody was sleeping, we escaped from our homes and rushed to the house. The front door was crumbling, so it wasn't hard for us to open it. When we entered the house, we saw tremendous stairs. It seemed it didn't have an end. At the end of the stairs, there was an old man.We couldn't see his face due to darkness. He asked what we had needed and we told him that we had come for sweets. When he was going down the stairs, we saw who he was. It was a ghost. 

1 I feel better if i do some exercises every day

2 If Dave is thirsty, he always drinks water

3 I get very tired at school if i go to bed late

4 My dad doesn't sleep well if he drinks coffee before bed

PS: Zero Conditional

If + Present Simple, + Present Simple

Present Simple

he she it            + Ve/es                                               -утвердительное

i you we they    +V infinitive                                      (v-verb)

he she it        + does/doesn't        + V infin           -при вопросительном\

i you we they  + do/don't              + V infin             и отрицательном(not)