8 . The word" community" in the third paragraph may mean_______ .
A. friends and relatives
B. local authorities
C. people living in the same district
D. both a and b
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4. Which of the following statements is NOT true?
A. People are the same, but people are also different.
B. Stages of life have different values in different cultures.
C. All people have the same emotions, such as love and hate, happiness and sadness.
D. All people feel the same emotions in similar situations.
6. The word "privilege" in the third paragraph means _____.
A. special gifts
B. special rights
C. special care
D. special treatment
纵波定义指的是
A. 振动方向和波的传播方向一致
B. 振动方向和波的传播方向相互垂直
C. 振源做横向振动的波
D. 振源做纵向振动的波
已知简谐振动方程x=a COS(bt+C),该振动的角频率为
A
B
C. c
D. x
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