题目

有一种橙色胶体溶液，在电泳实验中其胶粒向阴极移动。对这种胶体溶液进行下列处理，不发生聚沉的是 A.加硫酸钠溶液                                              B.加酒精溶液C.加硅酸胶体                                                 D.加氢氧化铁溶液I         a picture when the police         in.   [     ]A. draws ; came  B. was drawing ; came  C. draw; was coming  D. was drawing; was coming