Сhoose the right variant:
1. It's sunny today. It will\won"t rain.
2. Carla: 'Mum, the bus is late. I will\won"t be home until eight o'clock.
3. My brother's clever. I’m sure he will\won"t pass all his exams.

1. The correct variant for the first sentence is "It's sunny today. It won't rain." This is because the word "won't" is the contraction for "will not," and it indicates a negative future action. Since it is sunny, it means that there is no expectation of rain.

2. The correct variant for Carla's statement is "Mum, the bus is late. I won't be home until eight o'clock." This is because Carla is expressing that she expects to be late due to the bus being late. Again, "won't" is the contraction for "will not" and indicates a negative future action.

3. The correct variant for the third sentence is "My brother's clever. I’m sure he will pass all his exams." This is because the statement is expressing confidence in the brother's abilities, suggesting that he will successfully pass all of his exams. Therefore, "will" is used to indicate a positive future action.

Overall, in these sentences, "will" is used to indicate a positive future action, while "won't" is used to indicate a negative future action. It is important to pay attention to the context and the meaning of the sentence when choosing the correct variant.