液压缸的差动连接可提高（）。
参考答案：执行元件的运动速度
当上肢旋后伸直时，肘关节提携角（即外翻角）应为多少度（）。
A.1°～5°
B.6°～9°
C.10°～15°
D.16°～20°
E.21°～25°
Have you ever ___ to the museum ___ we paid a visit last year?
A．been; which
B．been; to which
C．gone; which
D．gone; to which
