50. From the passage we can learn that　　　　　 .

A. Machu Picchu has gone through lots of earthquakes

B. all of the mysteries of Machu Picchu have been solved

C. the city has never been discovered by people outside

D. Machu Picchu is the most valuable ruins in history.

49. The underlined word “interlock” probably means

A. put　　 　　　　　　　　　 B. fit　　 　　　　　　　　　　 C. meet 　　　　　　　　　　　 D. 1ie

48. Which of the followings is NOT a mystery of Machu Picchu?

A. Machu Picchu is called the “city in the clouds”.

B. Machu Picchu remains “the most famous ruins of South America”.

C. Machu Picchu is “the lost city” of the Incas.

D. Machu Picchu is the largest stone city of the world.

47．What is the best title for the whole passage?

A．Man-made clocks　　 B．Nature’s clocks

C．Time and clock　　　 　 D．How people keep time

D

Machu Picchu is considered to be a truly extraordinary archaeological(考古学的)discovery and is one of South America’s largest tourist sites. As many as one thousand visitors visit the ancient Ionian(印加文化的)ruins daily. What draws vacationers and adventurers to this remote location high in the Andes Mountains of Peru(秘鲁)?A large part of the attraction is the mysteries that surround Machu Picchu. For example，Machu Picchu is：Considered “the lost city” of the Incas because it was never found by Spanish invaders and was known to only a few local peasants for almost four hundred years.

The “city in the clouds”，Machu Picchu’s lasting beauty comes from the careful blending of its striking architecture with its mountaintop environment. Its greatest skill shows are in the stone structures，which equals t hat of the ancient Egyptians. The stone blocks were so appropriately cut that they fit together without the need for mud. The largest stones at Machu Picchu weigh as much as fifteen tons! It has been difficult to explain how the huge blocks were transported. The buildings, including many that have survived lots of earthquakes，contain stones which interlock so perfectly that fl knife cannot be forced between them. When compared to other ancient civilizations，it is difficult to understand how Machu Picchu could have been missed by the Spanish and lost from history for four hundred years.

For many of the mysteries of Machu Picchu being unsolved，it is clear why Machu Picchu remains “the most famous ruins in all of South America”.

46．In what way is the sand clock the same as the water clock in telling time?

A．Both of them have a neck．

B．Both of them have two glass balls．

C．Both of them can be used only once．

D．Both of them give the time by quantity．

45．According to the passage，how can animals know time?

A．They use body clocks．　　　　 B．They ask other animals．

C．They use the sun and the moon．D．They make something to tell time．

44．How could an ancient farmer know when t0 go back home from the field in the daytime?

A．By looking at the stars．　　 B．By looking at the moon．

C．By looking at the sun．　　 D．By feeling whether tired or not．

43. What’s the main idea of the passage?

A. Computers are stupid and inefficient

B. Computer errors are basically human errors

C. Computers can help department stores update the price list

D. Supermarket price errors are often made by computers

C

How did Ancient People Tell Time?

Natural ways of keeping time．

In ancient time．people had to use the sun and the moon to tell time．They got up when the sun came up and worked in the fields until the sun went down．

Man-made things

The sand c1ock is made of two glass balls joined by a narrow neck．The top ball was filled with sand．The sand slowly moved through the neck into the bottom ball．People knew how much time had passed when all the sand had fallen to the bottom ball．

People also made the water clock．They made a small hole near山e bottom of a pot．Then they filled the pot with water．Markings inside the pot showed how much time passed as the water dripped(滴)out of the hole．

Nature’s C1ocks in Living Things

Animals’ Body Clock

Animals do not need clocks to know time．They have a way of telling time by their bodies．Birds know when to fly to warmer places before winter．some animals know when to keep more f00d for the cold winter months．Some fish know when it is time to move up the river and lay eggs．

Plants have their own clocks

Plants als0 have their own clocks to keep time．Plants know when to open flowers or when to drop their leaves．

The Body Clock in Human Beings

People also h8ve their own body clocks．When we get used to our lives，our body clocks can be very accurate．It can tell us when it is time to wake up．It can also tell us when to eat or to go to sleep.

42. According to he author, which of the following statements is TRUE?

A．that high-tech cash register is anything but an electric eye

B. The grocery stores update the price list every other day.

C. There is no machine with intelligence today.

D. There are three lies in America

41. Grocery store price lists are updated by 　　　　　.

A. an employee　　 　　　　　　　　　　　　　　　　　　　　 B. a telephone receiver

C. an adding machine　 　　　　　　　　　　　　　　　　　 D. a typewriter