Ex. 1. Give the Past Indefinite Tense: I. He can speak English quite well. 2. He is to be at home at 7 o'clock. 3. She has to work at home today. 4. They must be very attentive at the lessons. Ex. 2. Complete the following sentences according to the models: Model I: I have missed many lessons and now I have to work very hard. The results of their experiments were bad, they had to repeat them. 1. He has worked very hard this month, he ... a little now. 2. This substance is very rare, if you want to use it, you . .. before the experiment. 3. They used analytical balances as they . . . very minute quantities. 4. The water is very cold, you ... before drinking it. Model II: I cannot attend the lecture as I am to be at home at six. 1. Don’t be late, the meeting ... at five sharp. 2. He…his research work by the end of this year, that’s why he is so busy. 3. The temperature ... to 100°C if you want to finish your experiment in time. 4. Don’t you know that she... at three, it will take her an hour to get here. Ex. 3. Fill in the blanks with “to have to” or “to be to”: 1. I can't go with them as I ... (to be) at the Institute at half past nine. 2. If you want to understand this phenomenon better, you ... (to look through) some articles devoted to this problem. 3. As this question is not solved the meeting .. .1 (to be put off 4. At ten a.m. he . . . (to make a report), I think it will be interesting to listen to him. 5. As he made many mistakes in his last work he . . . (to rewrite) it