驱动桥采用轮边减速器，从动件（）与车轮相连。
A.太阳轮
B.行星架
C.行星齿轮
D.齿轮
参考答案：B
氨基酸的平均分子量为128，现有一蛋白质分子由两条肽链组成，共有48个肽键，此蛋白质的相对分子量最接近于[ ]
A．6400
B．5550
C．5536
D．864
I, as well as she, ____ your close friend. We will share your joys and sorrows. [ ]
A. was
B. are
C. is
D. am
