有关胃肠双重对比造影剂，说法错误的是（）。
A.高浓度
B.低黏度
C.粗颗粒
D.黏附性强
E.不易沉淀
参考答案：C
I didn't understand _____, so I raised my hand to ask. [ ]
A. what my teacher says
B. what does my teacher say
C. what my teacher said
D. what did my teacher said
下列有关二氧化硅的叙述中错误的是
A．SiO2是酸性氧化物，它的对应酸是硅酸(H2SiO3)
B．二氧化硅易溶于水
C．SiO2可与CaO或NaOH反应
D．光导纤维的主要原料就是SiO2
