44. While driving, you are allowed to use your hand-held mobile phone to ___________.
A) chat with your assistant
B) make an emergency call
C)look for a U-Haul location
D) receive and send messages
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45. This passage is most probably taken from_________________
A) an announcement
B) an advertisement
C) an agreement
D) a notice
单选题：2､若驱动桥的一侧车轮转速为零，则另一侧车轮的转速( )｡
A. 一定为零
B. 等于差速器壳转速
C. 等于差速器壳转速的2倍
D. 以上答案都不对
单选题：3､汽车转弯行驶时，差速器中的行星齿轮()｡
A. 只有自转，没有公转
B. 只有公转，没有自转
C. 既有公转，又有自转
D. 以上答案都不对
单选题：4､设对称式锥齿轮差速器壳的转速为n0，左､右两侧半轴齿轮的转速分别为n1和 n2，则有 ( )｡
A. n1+n2=n0
B. n1+n2=2n0
C. n1+n2=1/2n0
D. n1=n2=n0
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