库仑滴定是通过（），来求算出被测物质的质量。
A.标准溶液浓度和体积
B.电解进行的时间和电流强度
C.未知液浓度和体积
D.库仑计指示
参考答案：B
He could hardly () his temper when he saw the state of his office.
A. hold in
B. hold up
C. hold off
D. hold out
