To become a Canadian citizen, you must have permanent resident status in Canada, and that status must not be in doubt. This means you must not be the subject of an immigration investigation, an immigration inquiry or a removal order (an order from Canadian officials to leave Canada).
孩子没有必要住满三年,但是父母办公民的时候已在加拿大经住了三年,然后申请公民至少一年,这4年孩子不在加拿大,不满足5年中2年的条件,移民身份就有问题。