我知道成为permanent resident之前在加拿大的时间折半计算。但之前拿student or work visa的有特别算法吗？Call centre的电话一直没打通，有知道的吗？多谢！
From: http://www.cic.gc.ca/english/citizen/howto-e.html
You must have lived in Canada for at least three years out of the four years right before the day you apply. For example, if you are applying for citizenship on 1 June 1997, we will count back to 1 June 1993. The time you spent in Canada BEFORE you became a resident will be counted as half time only if it happened within these four years. All the time you lived in Canada after you became a permanent resident counts as full time. If you came to Canada on a visa (for example on a student or work visa) before becoming a permanent resident, you may call the Call Centre (see below for the numbers) to find out when you can apply for citizenship.
From: http://www.cic.gc.ca/english/citizen/howto-e.html
You must have lived in Canada for at least three years out of the four years right before the day you apply. For example, if you are applying for citizenship on 1 June 1997, we will count back to 1 June 1993. The time you spent in Canada BEFORE you became a resident will be counted as half time only if it happened within these four years. All the time you lived in Canada after you became a permanent resident counts as full time. If you came to Canada on a visa (for example on a student or work visa) before becoming a permanent resident, you may call the Call Centre (see below for the numbers) to find out when you can apply for citizenship.
就连工作出差在外都要扣除的，学生回家当然也要扣除的了 
