题目

---You’ve made great progress in your studies of English, haven't you? ---Yes, but much___. A. remains to do   B.is remained to do   C. remains to be done   D. is remained to be done 答案：C 解析: 答句中的much后省略句为: progress in my studies of English remains to be made这是为了不重复, made用 done来代替.人类的卷舌与非卷舌由一对等位基因R和r控制，小明的父母均卷舌，而小明却不能。这说明卷舌是_____性状，小明的基因组合_________。 A．显性；rrB．隐性；rrC．显性；RrD．隐性；Rr