有一个点光源S，放在平面镜MN前，若镜MN不动，光源S以2m/s的速度沿与镜面成45°角的方向向右做匀速直线运动，如图所示，则光源S在镜中的像S′将（　　）

A．以速度4m/s沿SO直线方向向右平移

B．以速度2m/s沿垂直于SO方向向上平移

C．以速度2m/s沿垂直于SO方向向下平移

D．以速度4m/s沿SO直线方向向左平移

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Section B

Directions: Complete the following passage by using the words in the box. Each word can only be used once. Note that there is one word more than you need.

A．movement

B．largely

C．appearance

D．born E. alikeF. explained          G. common      H. frequently         I. final             J. learned

Perhaps the most famous theory, the study of body movement, was suggested by Professor Ray Birdwhistell. He believes that physical   41   is often culturally programmed．In other words, we learn our looks — we are not   42   with them．A baby has generally unformed face features. A baby, according to Birdwhistle, learns where to set the eyebrows by looking at those around — family and friends. This helps explain why the people of some areas of the United States look so much alike, New Englanders or Southerners have certain   43   face features that cannot be   44   by genetics. The exact shape of the mouth is not set at birth; it is   45   after. In fact, the   46   mouth shape is not formed until well after new teeth are set. For many, this can be well into grown-ups. A husband and wife together for a long time often come to look somewhat   47  . We learn our looks from those around us. This is perhaps why in a single country there are areas where people smile more than those in other areas. In the United States, for example, the South is the part of the country where the people smile most   48  . In New England they smile less, and in the western part of New York State still less. Many Southerners find cities such as New York cold and unfriendly, partly because people on Madison Avenue smile less than people on Peachtree Street in Atlanta. People in   49   populated areas also smile and greet each other in public less than do people in small towns.