Mario: Your beloved teacher has arrived here, Nina.Nina: I______ she ______ until tomorrow.
A. think; isn't coming
B. thought; wasn't coming
C. didn't think; was coming
D. didn't think; is coming
测定高锰酸盐指数时,什么当水样中的Clˉ含量比较高时,反应介质为碱性?当水样中Clˉ含量比较低时,反应介质为酸性?
Gene: Shall I open this window?Jodie: ______
A. No, please do.
B. I'd rather you didn't.
C. Please open this window.
D. I'd rather you hadn't done it.
水样中镉测定常用方法有二苯碳酰二肼分光光度法和硫酸亚铁铵滴定法()