Alabaman gave you the quote:
http://www.cic.gc.ca/english/resources/manuals/op/op10-eng.pdf If you look at this link, on page 7, it says:
In determining whether a permanent resident meets the residency test of physical presence for at least 730 days in a five-year period, A28(2)(b)(i) and (ii) state that:
28.(2)(b) it is sufficient for a permanent resident to demonstrate at examination
(i) if they have been a permanent resident for less than five years, that they will be able to
meet the residency obligation in respect of the five-year period immediately after they became
a permanent resident;
(ii) if they have been a permanent resident for five years or more, that they have met the
residency obligation in respect of the five-year period immediately before the examination [of
their residency status by a visa officer].
and:
For persons who have been permanent residents of Canada for more than five years, the only five-year period that can be considered in calculating whether an applicant has met the residency
obligation is the one immediately before the application is received in the visa office. A28(2)(b)(ii) precludes a visa officer from examining any period other than the most recent five-year period immediately before the date of receipt of the application.
and:
Even if a person had resided away from Canada for many years, but returned to Canada and
resided there for a minimum of 730 days during the last five years, that person would comply with
the residency obligation and remain a permanent resident. An officer is not permitted to consider
just any five-year period in the applicant's past, but must always assess the most recent five-year
period preceding the receipt of the application.
If you still can not understand this, I guess you will just have to remain confused because there is nothing else I can say to explain this to you.