观测表计时,要特别注意保持()与带电部分的安全距离。
A.柜门;
B.头部;
C.身体;
D.手足
参考答案:B
用下图电解水装置来探究水的组成。在该实验中,加入少量的氢氧化钠,可以增强水的导电性(但氢氧化钠在通电前后质量和性质不变)。将0.2克的氢氧化钠溶解在99.8克的水中并进行通电,当上述溶液中氢氧化钠的质量分数为0.5%时,被电解的水的质量为
A. 99.5g
B.40g
C.60g
D.6g
I was not ________by his many arguments ,so finally we agreed to differ. [ ]
A. prevented
B. convinced
C. expected
D. sent