皮皮学，免费搜题
登录
搜题
【单选题】
水杨酸和三氯化铁发生呈色反应的原理是A.
在中性或弱酸性(pH4-6)介质中，水杨酸所含羧基和Fe3+
B.
在中性或弱酸性(pH4-6)介质中，Fe3+氧化其所含酚羟基成醌
C.
在中性或弱酸性(pH4-6)介质中，水杨酸所含酚羟基与Fe3+生成有色配位化合物
D.
在中性或弱酸性(pH4-6)介质中，水杨酸所含酚羟基将Fe3+还原成Fe2+
E.
在中性或弱酸性(pH4-6)介质中，Fe3+水解
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】I've become good friends with several of the students in my school _____ I met in the English speech contest last year. [ ]
A.
who
B.
where
C.
when
D.
which
【单选题】I’ve become good friends with several of the students ___helped me in the English speech contest last year.
A.
who
B.
where
C.
when
D.
which
【单选题】--- Kathy, you’ve got a chance to deliver a speech at the conference? --- Yes, but how could I ______ the meeting date fixed so soon?. [ ]
A.
while
B.
as
C.
after
D.
with
【单选题】- Professor Johnson, I’ve won the first place in the Final English Speech Competition. - __________. It’ s really something.
A.
Come on
B.
Absolutely
C.
That’s a good point
D.
Good for you
【单选题】关于心电图,描述不恰当的是
A.
国际通用导联体系称为常规12导联体系
B.
在每一个导联正、负电极间均可画出一假想的直线,称为导联轴
C.
标准导联为双极肢体导联，反映某个肢体电位的变化
D.
胸导联属单极导联，包括V1-V6 导联
E.
加压单极肢体导联为单极导联，基本上代表检测部位电位变化
【单选题】— Are you confident about the English Speech Contest, Sally? — __________. I’ve got everything ready!
A.
Of course not
B.
It’s hard to say
C.
Sure, I am
D.
I am afraid not
相关题目：