题目

Dorothy was always speaking highly of her role in the play, ____, of course, made the others unhappy. A. who                       B. which C. this                      D. what   答案：Bof course 为插入语，若将项其去掉，则答案显然是B。甲基绿使DNA呈现绿色，吡罗红使RNA呈现红色，下列与吡罗红甲基绿染色剂用法相似的是 A．碘液          B．双缩脲试剂           C．斐林试剂          D．苏丹Ⅲ试剂