电子标签系统是计算机辅助拣货系统最常用的方法之一。
参考答案：对
Do not disturb me. I ________ letters all morning and have written ten so far. [ ]
A. write
B. have been writing
C. have written
D. was writing
农民可以自行在自留地、承包耕地上建住宅吗？
