1. If you want to pass the exam, you'd better ..... some studying. A) do B) to do C) doing D) done 2. If I knew the answer,

1. If you want to pass the exam, you\'d better do some studying. 2. If I knew the answer, I would tell you. 3. I will send you an e-mail when I am back in my country 4. By the time we arrived at the station, our train had left. 5. It was such a boring film that we left before the end. 6. Would you mind opening the window? It\'s very hot in there. 7. David\'s mother made him clean his bedroom.