对于倾角小于（）的皮带机，一般可不设制动器。
A.l°
B.4°
C.10°
D.13°
参考答案：B
Though the twins look alike, they _____in many aspects, especially in temperament and
personality
A．range
B．change
C．choose
D．differ
填料盒用久以后对填料环有什么影响？
