Помогите пожалуйста по английскому. Вот задания:  

1. Kate has been watering the flowers for forty minutes and has watered a half of them.

2. Jack has been reading humorous stories since two o'clock and has read three stories.

3. Helen has been doing the shopping for an hour and has bought ten books.

4. Bill has been writing the letters since five o'clock and has written two letters.

5. They has been building the houses since 2006 and has built five houses.