If you have held the immigration status of a “permanent resident” for about 3 years and spent 75% of this time in Canada, you may qualify for Canadian citizenship. This only applies if you have not committed any crimes. You can then obtain Canadian citizenship through another application procedure which may, depending on age, include an examination.
Many countries of origin prohibit dual citizenship and force their citizens to choose between either the old or the new citizenship. Other countries such as Germany and Austria allow it under certain conditions which you must demonstrate concretely in an application to your country of origin. It is generally important to have all special permits to hand before accepting Canadian citizenship. For Germany and Austria, we can recommend you a very experienced law firm for these matters.
Other countries such as Switzerland are very generous in allowing multiple citizenship.