由于与 Fe 3+ 与铬黑 T 的配合物的稳定性比F e 3+ 与 EDTA 的配合物的稳定性大,所以 Fe 3+ 对有铬黑 T _____ 作用。 EDTA 法测定水的总硬度时通常用 _________________ 掩蔽 Fe 3+ 、 Al 3+ 等少量共存离子,在测定钙硬时用 _________________ 掩蔽 Mg 2 + 。(填写物质的名称)
【简答题】Unit 3 Security Part I Listening Comprehension Section A Directions: In this section, you will hear three news reports. At the end of each news report, you will hear two or three questions. Both the n...
【简答题】Unit 7 配套练习题1-7题 (新闻部分) Section A Directions: In this section, you will hear three news reports. At the end of each news report, you will hear two or three questions. Both the news report and the ques...