Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbers blanks

Deep sleep is important for everyone. The actual amount of sleep depends (27)_____ your age. A young child ought to sleep ten to twelve hours, and a teenager about nine hours. Adults differ a lot in their sleeping habits. For most of them, seven to eight hours a night is (28)_____, but some sleep longer, while others manage with only four hours.

For a good night, having a comfortable (29)_____ to sleep is very important. Also, there should be (30)_____ of fresh air in the room. A warm drink sometimes helps people to sleep, although it is not a good idea to drink coffee immediately before going to bed.

If you have to travel a very long distance, try to go to bed earlier than usual the day before the journey. This will help you to feel more (31)_____ when you arrive.