这个是加拿大移民局的问答,大家看看只去美国是不是不需要多次签的意思? Single-entry temporary resident visa
If you have a single-entry temporary resident visa, you will generally need a new single-entry visa to come back to Canada. You can request to return to Canada on your original single-entry temporary resident visa, if:
you will only visit the U.S. or St. Pierre and Miquelon; and you will return to Canada before the end of your approved stay in Canada.
Single-entry temporary resident visa
If you have a single-entry temporary resident visa, you
will generally need a new single-entry visa to come back to Canada.
You can request to return to Canada on your original
single-entry temporary resident visa, if:
you will only visit the U.S. or St. Pierre and Miquelon;
and
you will return to Canada before the end of your approved
stay in Canada.