Few of them came to the city, ?[ ]
A. don't they
B. do they
C. didn't they
D. did they
答案:D
数字逻辑电路中三种基本逻辑关系是什么?能实现这三种逻辑关系的电路分别是什么?
肾的结构和功能的基本单位是 。