现场污秽度评估用的精密天平检测精准度要求为（）mg。
A.0.05
B.0.1
C.0.2
D.0.3
参考答案：B
After five years of preparation，Shanghai presented the world ______ many said was the greatest Special Olympics.
A．when
B．what
C．where
D．which
正极搭铁的汽车，装用直流发电机时，电流表应怎样接线？
