测得某样品的余氯为1.0mg/L，准确测定其pH的方法是（）
A.pH试纸法
B.比色法
C.滴定法
D.重量法
E.电位计法
参考答案：E
A．，正电荷
B．，正电荷
C．，负电荷
D．，负电荷
After he lost his job, he ________ debt but eventually paid it off.[ ]
A. went into
B. got into
C. ran into
D. tried out
，正电荷
，正电荷
，负电荷
，负电荷