Most people who travel long distances complain of jetlag（喷气式飞行时差反应). Jetlag makes

Most people who travel long distances complain of jetlag(喷气式飞行时差反应). Jetlag makes business travelers less productive and more prone【C1】______ making mistakes. It is actually caused by【C2】______ of your "body clock"-a small cluster of brain cells that controls the timing of biological【C3】______ . The body clock is designed for a 【C4】______ rhythm of daylight and darkness, so that it is thrown out of balance when it【C5】______ daylight and darkness at the "wrong" times in a new time zone. The【C6】______ of jetlag often persist for days 【C7】______the internal body clock slowly adjusts to the new time zone.

Now a new anti-jet, lag system is【C8】______ that is based on proven【C9】______ pioneering scientific research. Dr. Martin Moore-Erie has【C10】______ a practical strategy to adjust the body clock much sooner to the new time zone【C11】______ controlled exposure to bright light. The time zone shift is easy to accomplish and eliminates 【C12】______ of the discomfort of jetlag.

A successful time zone shift depends on knowing the exact times to either【C13】______ or avoid bright light. Exposure to light at the wrong time can actually make jetlag worse. The proper schedule【C14】______ . light exposure depends a great deal on【C15】______ . ravel plans. Data on a specific flight itinerary(旅行路线) and the individual's sleep【C16】______ are used to produce a Trip Guide with【C17】______ on exactly when to be exposed to bright light.

When the Trip Guide calls【C18】______ bright light you should spend time outdoors if possible. If it is dark outside, or the her is bad,【C19】______ you are on an aeroplane, you can use a special light device to provide the necessary light【C20】______ for a range of activities such as reading, watching TV or working.

【C1】

A．for

B．from

C．to

D．of