It has been documented that during World War II, America's armed forces once tried formation flight to save fuel.
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The upwash experience may save propelling energy as well as reducing resistance.
A. Right
B. Wrong
Which of the following does NOT belong to products that help create people's habits?
A. Tide
B. Crest
Colgate
D. Unilever
The author's attitude toward the influence of advertisement on people's habits is______.
A. indifferent
B. negative
C. positive
D. biased
The three Ds mentioned in the last paragraph are______.
A. auction houses' favorites
B. contemporary trends
C. factors promoting artwork circulation
D. styXes representing Impressionists