STZ-treated rats， which are totally defective in insulin secretion， are a common model of Type 1 diabetes.
先看几道考题，能做对就不用往下看了:The world _____ we live is made up of matter.A. on which B. of which C. at which D. in which。
在介词+关系代词结构中，在介词前面可以加代词，名词，数词，形容词的比较级，最高级，短语等。This is the school in which I taught for 30 years. 这就是我教了30年书的学校。
