回复：Need your suggestion for a business trip to Canada

You can use your Canadian PR to enter canada with no problem so far, because the minium requirement for keeping Canadian PR is to stay in Canada for at least two years within five year period.

But the problem is that US doesn't allow you to have another PR from other country, I think same with Canada, so if US finds out you have Canadian PR, they will revoke your GC, it's your call on what you want to do with your dual PR status which by law is illegal.