2.【多选题】 data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAtwAAACwCAYAAAA8ALlhAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAACYPSURBVHhe7d37iyRX3cfxsz7
4.【单选题】 data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABGYAAABACAYAAABY83HLAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAJZpSURBVHhe7V0FfFRH9z3E3d09IcGCu1Mo0hZKhbobdW
7.【判断题】图中所示直线为铅垂线 data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAOsAAADmCAYAAAA0lHILAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAH6eSURBVHhe7b0HoCVHdSb8dbjphXmT82hGMxrlnIVASAIhgZ
10.(单选题)区域V中，填充线性、各向同性、非均匀的电介质（介电常数为
