单项选择题
A.2 B.1 C.0.5
A.AB=70mm,BC=60mm,CD=80mm,AD=95mm B.AB=80mm,BC=85mm,CD=70mm,AD=55mm C.AB=70mm,BC=60mm,CD=80mm,AD=85mm D.AB=70mm,BC=85mm,CD=80mm,AD=60mm
A.双曲柄 B.曲柄摇杆 C.双摇杆