Wanitasays Bob looks OK though he is not that handsome.
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What coffee does Al want?
A. black coffee
B. white coffee
C. black coffee with sugar
D. white coffee with milk
人的自然视线一般是水平线往下45°。
A. 对
B. 错
一个人的临界视角越大,则此人视力就越好。
A. 对
B. 错
眼睛能感觉的光的波长范围约为40-760NM。
A. 对
B. 错
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