1. If he (is) late, he (will miss) the train.
2. If he (misses) the train, he (will have) to take a bus.
3. If he (takes) a bus, he (will arrive) at 9:30.
4. If he (arrives) at 9:30, he (will meet) our teacher.
5. If he (meets) our teacher, she (will ask) him about the party.
6. If she (asks) him about it, he (will tell) her the truth.
7. If he (tells) her the truth, she (will know) everything.
8. If she (knows) everything, she (will be) angry.
9. If she (is) angry, she (will give) us a lot of work to do.
10. If she (gives) us a lot of work to do, I (shall be) very busy.