If you have ever flown across several time zones，you must have experienced jet lag.You arrived in a new time zone，but your body was still living on the time in the old time zone.You were wide-awake and ready for dinner in the middle of the night，and you wanted to sleep all day.
   People suffer from jet lag because all living things have a biological clock.For example，plants open their leaves and begin producing food at sunrise.When spring arrives，birds start looking for a mate.When winter comes，they fly to a place with a warmer climate.Some insects like honeybees also seem to set their alarm clocks to wake them up to look for food.
   Some French scientists did an experiment with honeybees.They put out sugar water every morning at 10：00 and at noon，and the bees came to drink the water at exactly the right time.Then the scientists put the sugar water in a room that was brightly lit 24 hours a day. They started putting the sugar water out at 8：00 p.m.It took the bees a week to find it at the different hour，but from then on they came to eat in the evening instead of in the morning.Later the scientists took the honeybees to New York.The bees came for the food at the time their bodies told them，only when it was 3：00 p.m. （New York time）.Their bodies were still on Paris time.
   Humans，like other animals，have a biological clock that tells us when to sleep and eat.It causes other changes，too.Blood pressure is lower at night，the heartbeat is slower，and the body temperature is a little lower.The honeybees in the experiment reset their biological clock for different feeding hours.Humans do this，too.Our bodies are controlled by a biological clock，but we can learn to reset it at a different time.

（1）What is the passage about？

D

D

A．Honeybees.
B．Jet lag.
C．Time zones.
D．Biological clock.
（2）How many examples are shown to prove that all living things have a biological clock in Paragraph 2？

C

C

A．Two.
B．One.
C．Four.
D．Five.
（3）When the honeybees were taken to New York，they came to drink the sugar water

A

A

.
A．a(chǎn)t 8：00 p.m.Paris time
B．in 24 hours
C．in the morning
D．a(chǎn)t 3：00 p.m.Paris time
（4）What is the purpose of showing the experiment with honeybees？

C

C

A．To prove that all living things have a biological clock.
B．To explain how honeybees set their alarm clocks.
C．To show that living things can reset their biological clock.
D．To tell us that honeybees look for sugar water to survive.
（5）What is NOT TRUE according to the passage？

D

D

A．Both human blood pressure and body temperature are lower at night.
B．Human beings are able to get used to a new time zone.
C．People suffer from the jet lag because of the biological clock.
D．The biological clock has no effect on us except telling us when to sleep and eat.