A. 浏览器内核 B. 操作系统位数 C. 操作系统版本 D. 浏览器版本
A. check=check B. selected=selected C. checked=checked D. select=select
A. select count(1) from ab where a2>0 group by a1,a2 B. select a3,count(1) from ab where a2>0 group by a1,a2 C. select a1,count(1) from ab where a2>0 group by a1,a2 D. select a1,count(1) from ab where a2>0 group a1
A. 应用层 B. 链路层 C. 物理层 D. 传输层
A. 应用层 B. 数据层 C. 传输层 D. 网络层