我想申请B2签证。其中有一条要求我不太明白，请大家帮帮忙，解释一下。要求如下：
B2: Visitor for Pleasure
• DS-156 (application form).
• Valid Passport (at least 6 months).
• Proof of legal status in Canada: original or certified copy.
• One passport-size photo.
• Older passports containing previous visas.
• Documents substantiating previous legal status in U.S.
• US$100 non-refundable application fee.
• Reciprocity fee (if applicable).
• Proof of sufficient funds to cover all expenses while in the U.S.
• Proof of ties/residence in a country outside the U.S. which have no intentions of abandoning.
• Evidence which show the purpose of trip.
在这里：Proof of ties/residence in a country outside the U.S. which have no intentions of abandoning. 是什吗意思？
万分感谢！！！！！
B2: Visitor for Pleasure
• DS-156 (application form).
• Valid Passport (at least 6 months).
• Proof of legal status in Canada: original or certified copy.
• One passport-size photo.
• Older passports containing previous visas.
• Documents substantiating previous legal status in U.S.
• US$100 non-refundable application fee.
• Reciprocity fee (if applicable).
• Proof of sufficient funds to cover all expenses while in the U.S.
• Proof of ties/residence in a country outside the U.S. which have no intentions of abandoning.
• Evidence which show the purpose of trip.
在这里：Proof of ties/residence in a country outside the U.S. which have no intentions of abandoning. 是什吗意思？
万分感谢！！！！！
