It can be inferred from the passage that animals that are prey rarely experience dream sleep because they

• A、have evolved further than predators
  
  

• B、are particularly intelligent animals
  
  

• C、need less sleep than predators
  
  

• D、would be caught if deeply asleep
  
  

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Supermarket

Most supermarkets need a very large floor area, sometimes at least ten times as big as that of an ordinary shop. There are usually two doors, one as an entrance and the other as an     31   . The rest of the side facing the street is largely of plate glass, with goods or advertising material displayed. The other three walls are     32    decorated in light colors, giving an     33   of cleanliness and brightness.

At right angles to the window stretch long structures about six feet  ___34____ with a number of shelves on each side. Similar shelf units or frozen food containers extend round the walls. Broad aisles (通道) between the shelf units and ample (足夠的) space between them and the window and also the far wall     35    room for the circulation of many people.    36   commodities (商品) , in tins,  bags, boxes or other containers, are stacked (堆放) in groups on the shelves, and each group is   37   with a price ticket. Metal baskets near the entrance are taken by the shoppers who collect the goods that they  ___38____ from the shelves.

Between the shelf units and the windows are a number of small corners about three feet high. Beside each  ___39____ a cashier, who operates a machine for the totaling cost of each customer's purchases. The customer places the basket at one end of the counter so that it can be emptied by the cashier who records the price of the commodities one by one, before putting each on a moving section of the counter top. The cashier finally hands a printed slip recording all prices to the  ___40____, who pays the total, collects the bag and leaves.

A. sits	B. high	C. exit
D. customer	E. various	F. small
G. tall	H. normally	I. allow
J. impression	K. labeled	L. select

Task 2

21. In most cases of cloud-to-ground lightning, the ground's surface__________

22. One form of lightning that is ball lightning. __________

23. Cloud lightning looks like a ribbon when its lighting channel__________

24. Although not fully understanding processes of lightning, man__________

25. Lightening can__________

A. occurs most infrequently

B. is shifted sideways by strong winds

C. strike twice or more in the same spot

D. is equipped with a good knowledge of various forms of lightning

E. is estimated at 20 million a year

F. is positively charged