n.定界符；分隔符
The row delimiter is always the line break and cannot be chosen freely. 行定界符总是换行符,不能自由选择。
The delimiter is usually a comma. 分隔符通常是一个逗号。
If no semicolon is present, a period is the field delimiter. 如果没有分号,则使用句号作为字段分隔符。
