Complete the sentences with have to, has to, had to, will have to.

Example: Next geography lesson they will have to present their project about the wonders of nature. 1. I have to finish my homework before I go out. 2. My sister had to go to the doctor yesterday. 3. They will have to study hard for the exam next week. 4. She has to clean her room today. 5. We had to cancel our plans because of the rain.