本人现住美国，2004年5月取得加拿大访问签证(SINGLE ENTRY)，有效期自5月17日至11月17日。期间本人曾于6月13日进入加拿大(加拿大移民局印章6月13日)，6月20日离境。请问，根据下面的有关加拿大访问签证的规定，本人是否仍可持同一签证在11月17日前再次访问加拿大而不必申请新签证？谢谢！(另，本人曾于7-8月间回过中国)。
A SINGLE ENTRY visa allows entry to Canada ONCE from ANY country. The amount of time you are allowed to remain in Canada (up to 6 months) will be shown by an entry stamp in your passport. While staying in Canada, if you are allowed entry to the United States, you may travel back and forth between the USA and Canada during the time allowed by your entry stamp. Entry to Canada is always at the discretion of the Immigration Officer at the Port of Entry. (http://www.dfait-maeci.gc.ca/can-am/menu-en.asp?act=v&did=2740&mid=8&cat=622&typ=1，Canadian Consulate General in Detroit.)