求翻译：我，王立达，在新加坡国立大学注册为医学本科全日制学生，想邀请我的母亲肖明东，1960年6月8日出生，来新加坡国立大学访问，时间从2011年 月 日起，此次访问的目的是探亲及旅游，期间将留在我身边上述地址，我会确保她在授权逗留期满前离开新加坡。我对您为我母亲发出签证提供的帮助不胜感激。是什么意思？

I, Wang Lida, Singapore National University registered as full-time undergraduate students of medicine, would like to invite my mother xiaomingdong, born on June 8, 1960, Singapore National University access time from the date of 2011, that this is the purpose of family visits and tourism, will stay on my side during that address, I will ensure that she authorized leave prior to the expiry of stay in Singapore. I issued visas to you for my mother's help will be highly appreciated.