题目

 Seeing their teacher _______ into the classroom, they stopped _______ at once. A. walk; telling                                     B. entering; to speak        C. enter; to tell                                           D. walking; talking    答案：D清洗蓝莓果实时，果盘内会出现少量紫色汁液，吃蓝莓时，手指会被染成紫色．这些紫色汁液来自果实细胞的（ ）A.细胞壁B.线粒体C.叶绿体D.液泡