磁致伸缩式液位仪探棒测量的液位高度可准确至（）。
A、±0.1mm
B、±0.3mm
C、±0.5mm
D、±0.7mm
参考答案：C
---Alice, you look puzzled, Have you understood it?
---Yes．I _____another problem just now．
A．l have thought of
B．am thinking of
C．had thought of
D．was thinking of
