问题
选择题
Chinese scientists have produced an embryo of a giant panda through cloning technology,_____ is a breakthrough ______ could save the endangered animals.
A．that; which
B．which; that
C．which; what
D．that; what
答案
答案：B
题目分析： 句意：科学家已经通过克隆技术复制出大熊猫的胚胎，这是能够拯救濒危动物的一项突破。第一空填which，引导非限制性定语从句，指代前面的内容，that不能引导非限制性定语从句，第二空填that修饰breakthrough，在定语从句中做主语，所以选B。