37. I didn’t have the key. I couldn’t get into the house. (Because)
⇒ Because I didn't have the key, I couldn't get into the house.
39. You eat too much. You will be fatter. (More)
⇒If you eat more,you will be fatter.
38. I like Chinese. I can’t speak it perfectly. (Wish)
⇒I wish I could speak Chinese perfectly.
40. They are going to visit the villagers. Their houses were swept away by the unexpected flash flood. (Whose)
⇒They are going to visit the villagers whose houses were swept away by the unexpected flash flood.