—Bob speaks Chinese quite well.

—Yes, _____. Both of them practise ______ Chinese every day. [ ]

A. so does Tom, speaking

B. Tom does so, to speak

C. so Tom does, speaking

D. so does Tom, to speak.

质量控制过程中，下列因素属于系统因素的是（）

A、温湿度微小波动

B、原材料规格、品种有误

C、原材料的微小差异

D、机器设备正常磨损