确定尺寸精确程度的等级叫做公差等级。
参考答案：对
The young man stopped and looked back as if ______ whether he was being followed.
A．seeing
B．to have seen
C．having seen
D．to see
主营业务收入不包括( )。
A．物业管理收入
B．物业经营收入
C．物业小修收入
D．物业大修收入
