题目内容

___ six years since I began to study English.

A. It is
B. I have been
C. There are
D. It was

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___ in the room at that time.

A. Someone were
B. Nobody was
C. Who is
D. He are

工业机器人传统上一直采用直流伺服电机，因为它基本可以实现免维护。

A. 对
B. 错

除个别运动精度不高、重负载或有防爆要求的机器人采用液压、气压驱动外，工业机器人多采用交流伺服电机驱动。

A. 对
B. 错

陀螺仪传感器可以测量机器人的加速度。

A. 对
B. 错