Can parents immigrate after their son goes to Canada for college?

It is stipulated that the relatives that immigrants can bring are wives/husbands and children under 18. (The above can be directly immigrated with him. )

The government is unwilling to accept the elderly, thinking that it will bring a burden to the government (and those who can't work in Canada), and the government needs to pay a lot of money every year. Moreover, after immigration, you will not enjoy Canadian citizen benefits immediately, and you need to wait for a long time.