9.One of the easiest ways to help your health is just to sleep eight hours or more every night. _____9_____ , more and more people in the world are not sleeping enough. According to the World Health Organization, over half the people in the world may be sleep-deprived. The result of this is not just a lot of tired people; in the United States alone, sleepy drivers_____10_____ at least 100,000 car crashes and 1500 deaths a year.
According to experts, sleep is like _____11_____ . If you sleep only five hours a day, you don’t “get used to it,” but instead, build up a “sleep deficit.” “It’s like a credit card,” says Dr. Mass. “You are only _____12_____ time. You always have to pay it back.” The more hours you don’t sleep, _____13_____ you should sleep to “pay back” the hours on your “sleep credit card.” 【題組】9. (A)Moreover (B)However (C)Therefore (D)Because