（在数字串前后加 " " 或' ' 或 tab等空白内容都是行不通的，excel会自动去掉这些。除非你在数字串中间加，当然这样就不是我们要的结果了）
解决方案之一：<td style="mso-number-format:'\@';">100821199909091234</td>
增加了 style="mso-number-format:'\@';" 样式后 可以解决 ，（以上为亲自测试过，可行）！
其他自定义单元格格式 样式
| mso-number-format:"0" | NO Decimals |
| mso-number-format:"0\.000" | 3 Decimals |
| mso-number-format:"\#\,\#\#0\.000" | Comma with 3 dec |
| mso-number-format:"mm\/dd\/yy" | Date7 |
| mso-number-format:"mmmm\ d\,\ yyyy" | Date9 |
| mso-number-format:"m\/d\/yy\ h\:mm\ AM\/PM" | D -T AMPM |
| mso-number-format:"Short Date" | 01/03/1998 |
| mso-number-format:"Medium Date" | 01-mar-98 |
| mso-number-format:"d\-mmm\-yyyy" | 01-mar-1998 |
| mso-number-format:"Short Time" | 5:16 |
| mso-number-format:"Medium Time" | 5:16 am |
| mso-number-format:"Long Time" | 5:16:21:00 |
| mso-number-format:"Percent" | Percent - two decimals |
| mso-number-format:"0%" | Percent - no decimals |
| mso-number-format:"0\.E+00" | Scientific Notation |
| mso-number-format:"\@" | Text |
| mso-number-format:"\#\ ???\/???" | Fractions - up to 3 digits (312/943) |
| mso-number-format:"\0022£\0022\#\,\#\#0\.00" | £12.76 |
| mso-number-format:"\#\,\#\#0\.00_ \;Red\-\#\,\#\#0\.00\ " | 2 decimals, negative numbers in red and signed |