Fill in the blanks with the correct form of verbs given in the brackets.
1. Someone ____________ (knock) at the door.
2. Good boys ____________ (obey) their elders.
3. Water ____________ (boil) at 100°C.
4. Birds ____________ (fly) in the air.
5. I ____________ (receive) your letter yesterday .
6. My father ____________ (leave) for Mumbai tomorrow.
7. The child ____________ (cry) because it cannot find its mother.
8. My mother ____________ (teach) in a college. She ____________ (go) there in the morning.
9. He ____________ (go) to Shimla tomorrow.
10. Thomas Edison ____________ (invent) the electric lamp in 1879.
