选择题:—Does Liu Hui serve in the army? —No, but he _____

题目内容:
—Does Liu Hui serve in the army? —No, but he ________ in the army for three years.
A.served
B.has served
C.is serving
D.would serve
参考答案:

用离子选择电极以标准加入法进行定量分析时,应要求标准溶液()

用离子选择电极以标准加入法进行定量分析时,应要求标准溶液()A (A)体积要大,浓度要高B (B)体积要小,浓度要低C (C)体积要大,浓度要低D (D)

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