In temperate regions the growth rings on turtles’ epidermal plates reflect seasonal variations in growth.

单项选择题The study was the first to tell the difference between 7 and 8 hours of sleep a night.

单项选择题Sleeping for less than 5 hours each night is better than sleeping for 5 hours.

单项选择题Most of the participants slept for 7 hours a night during the study.

单项选择题The findings indicate that it is all right to sleep for 6.5 hours a night.

单项选择题The study shows that the longer you sleep each night, the longer you’ll live.